Chapter+1

toc __Chapter 1 Section 1-__

 * What do you see?**
 * The yellow and orange car got into an accident.
 * The blue car reacted fast enough to stop short of the crash (skidded).
 * The orange car got the most damage.
 * The mountains in the background may have distracted the driver and caused the accident.
 * What factors affect the time you need to react to an emergency situation when driving?**
 * If the person is paying attention.
 * Speed of the car.
 * Physical condition of the car (weight, tires, breaks, how old the car is, etc.)
 * The road conditions (snow, ice sleet, rain, wet gravel, etc.)

1.a.- The estimate about how fast my foot could be transferred from gas to break would 1/4 of a second. 2.a.- The estimate about how fast my foot could be transferred from gas to break after my classmate would clap is 1/2 a second. 1a- 1b- The average reaction time would be .17 seconds.
 * Investigate**
 * Foot to Brake
 * || Time in seconds ||
 * Trial 1 || .38 ||
 * Trial 2 || .341 ||
 * Trial 3 || .32 ||
 * Foot to brake after a classmate claps
 * || Time in seconds ||
 * Trial 1 || .35 ||
 * Trial 2 || .41 ||
 * Trial 3 || .29 ||
 * Method A**- Starting and Stopping Stopwatches
 * || Difference between times ||
 * Trial 1 || .09 ||
 * Trial 2 || .19 ||
 * Trial 3 || .23 ||


 * Method B-** Catching a ruler

1a- 1b- The average distance the meter stick fell was 8.333333 cm. 1c- According to the chart my average reaction time would be about .12 seconds.
 * || Distance the meter stick fell (cm) ||
 * Trial 1 || 11 cm ||
 * Trial 2 || 5 cm ||
 * Trial 3 || 9 cm ||

1: a- The reaction times differ by person because everybody has their own reaction time. Some people are a lot slower and opposite that, some people have a lot faster reaction times. Meanwhile, some people have the same reaction times. b- I think the meter stick drop most accurately finds the reaction time because there is no stopping of the stopwatch, but instead where the persons fingers end up. When you stop the stopwatch you might be a little delayed which can mess up (slow down) the persons reaction time.
 * Comparing Methods of Measuring Time-**

2: a- The slowest time between our group and another group was .23 (27 cm) seconds from Colin and the fastest time was .08 seconds (3 cm) from Steven. This gives us an average time of .155 seconds. b- Yes I think reaction times vary for people of the same age because, when we compared answers Colin and Steven had a vastly different reaction time. But, I also think that younger people will have a faster reaction time than older people.

1a- The reaction time with needing to make a decision is slower than that of without needing to make a decision. 2. a- The average reaction time with a decision and a distraction is slower then that of without making a decision. b- Texting, Drinking, Talking, Singing, Looking out the window, Doing makeup, Looking at GPS, Talking on the phone, Adjusting the heat/ air conditioning, Eating. 1. Distractions while driving will effect reaction time because it will slow down the drivers reaction time. Because of this, the driver faces a life or death decision. Distractions while driving can kill you if you do not react fast enough to avoid the accident. 2. Driving while under the influence of drugs or alcohol is illegal because some of them can cause the driver to slow their reaction time. 3. Three factors in addition to distractions and drugs or alcohol are accidents that took place in front of them, multitasking, and people that fall asleep.
 * Reaction time with distractions-**
 * || Distance the meter stick fell (cm) || Average ||
 * Trial 1 || 68, 18, 87, 17, 86 || 55.2 cm ||
 * || Distance the meter stick fell (cm) || Average ||
 * Trial 1 || 52, 20, 45,15, 25 || 31.4 ||
 * Physics Talk- Checking Up**

1. a. b. c. The chart from "1B" is very similar to that of the chart found on page 10 of the investigate. They both have the same slope.
 * Active Physics Plus: Calculating Reaction Time**

- What factors affect the time you need to react to an emergency situation while driving? 1. Reaction time is the amount of time it takes for someone to react to something, with or without distractions. 2. There were several ways we measured reaction time during this section. One of the ways we measured reaction time was use a stop watch to time how fast we could move our foot from the gas to the break. Another was to see how fast we could stop a watch compared to our partner. And the other way we measured reaction time was dropping a ruler and using the formula: d=1/2at^2 to determine how much time it took to fall. The times of other people in our class ranged from .155 seconds to .23 seconds. 3. 4. Reaction time is very relevant to driving safely. This is because if you have a slower reaction time you have a higher chance of not being able to react quick enough to avoid an accident. Whereas if you had a faster reaction time you might be able to avoid the accident. Also, knowing your reaction time might cause yourself to take precautions like staying farther back from the car in front of you to give you a greater reaction time. 1. This graph represents people on my baseball team (ages vary from 16-17) This graph represents people at a bar (ages vary from 27- 66) 2. The reaction times obtained from the kids on my baseball team and from the people at the bar varied compared to those of the kids in our class. For example, the kids on my baseball team were pretty close in comparison to those of the people in our class. The reason for this might be because they are of the same age group. But, the reaction time of the people at the bar compared to those of the kids in our class probably because of the age difference and also because the people at the bar were drinking and therefore their reaction time was slowed. 4. Yes, a race car driver would need a faster reaction time then that of a person driving in a school zone because when you are driving a race car you are driving at a much faster speed. When you are driving a race car you are driving at a much faster speed as are the people next to you. You also have to worry about other cars speeding up to pass you. Which, at those speeds, if you don't have a fast reaction time could be deadly. Meanwhile, in a school zone you are going at a much slower speed which gives you more time to react to things like kids crossing the street. 5. Things like alcohol, talking on a cell phone and changing the radio can dramatically slow down your reaction time, which, in turn can cause for more accidents. 6. Some consequences of those driving with a slow reaction time, rather then quick, can face problems such as not being able to avoid accidents with other cars and even people crossing the street in front of them. Also, maybe the light changed as they were about to go through the intersection and they didn't react fast enough to stop at the light and instead went through it. Doing this can cause accidents and at the very minimum cause you to get a ticket. 7. Even though teenagers have a faster reaction time then older, more experienced drivers, their insurance costs more because they tend to be more reckless and drive at faster speeds which can cause accidents. Also, they are not nearly as experienced which can also cause problems. 8. Knowing your own reaction time can cause you to be a safer driver because then you can take the necessary precautions to avoid an accident. For example, you can stay at a distance behind the car in front of you where you know you will have time to stop if they get into an accident.
 * What do you think now?**
 * Some of the distractions we observed during the investigation were dialing a number on the phone while driving or changing the radio while driving. Also another distraction was the red and green when trying to catch the ruler as quick as possible. As we did the investigate with the distractions we found out that we reacted much slower then we did when we did the investigate without the distraction.
 * Physics Essential Questions-**
 * Physics to Go-**
 * || Distance caught on ruler (cm) || Reaction Time (s) ||
 * Person 1 || 8 || .1277 ||
 * Person 2 || 10 || .1468 ||
 * Person 3 || 9 || .1355 ||
 * Person 4 || 13 || .1629 ||
 * Person 5 || 6 || .1101 ||
 * Person 6 || 15 || .1749 ||
 * Person 7 || 20 || .2020 ||
 * Person 8 || 15 || .1749 ||
 * Person 9 || 16 || .1807 ||
 * Person 10 || 12 || .1565 ||
 * Person 11 || 6 || .1101 ||
 * Person 12 || 18 || .1917 ||
 * Person 13 || 14 || .1690 ||
 * Person 14 || 10 || .1468 ||
 * Person 15 || 8 || .1277 ||
 * Person 16 || 9 || .1355 ||
 * Average || 11.8125 || .1533 ||
 * || Distance caught on ruler (cm) || Reaction time (sec) ||
 * Person 1 || 18 || .1917 ||
 * Person 2 || 17 || .1863 ||
 * Person 3 || 20 || .2020 ||
 * Person 4 || 22 || .2119 ||
 * Person 5 || N/A* || N/A ||
 * Person 6 || 14 || .1690 ||
 * Person 7 || 17 || .1863 ||
 * Person 8 || 19 || .1969 ||
 * Person 9 || 20 || .2020 ||
 * Person 10 || 18 || .1917 ||
 * Average || 18.33 || .1930 ||
 * - represents that someone did not catch the ruler and therefore there was no reaction time for that person.

__Section 2-__

 * What do you see?**
 * A guy walking parallel to a measuring tape comparing the amount of steps to the length. (bigger steps)
 * I see the same thing as the guy walking parallel to the measuring tape, but instead its a little girl. (smaller steps)
 * I see another kid with a notepad and calculator taking measurements and recording it.
 * The kids are walking up the hallway and the numbers are getting larger.


 * What do you think?**
 * No, they didn't necessarily make a mistake. That is because one of them could have used a measuring device that isn't as precise as the other. Or, maybe they measured the wrong dimension of the object. Then again maybe they both measured the object the wrong way and neither of their numbers are viable.
 * No, I don't think one of them made a mistake, I just think one of the students had a more precise measurement then the other, but that doesn't make the other one wrong.


 * Investigate-**

2.
 * || Number of Strides || Distance of Stride (cm) || Total Distance (cm) ||
 * Trial 1 || 16 || 41 || 656 ||

5.a. For the most part the measurements agree, most of them varying by about 100 cm or so. But, there were some people who's measurements acted as outliers. Overall most of the measurements were the same. b. I think there could be several reasons for the variations in the measurements. For example, some people may have strides longer then others which could have caused a discrepancy in the measurements. Also, some people may have measured their stride wrong (maybe they went from heel to toe instead of heel to heel). c. Maybe everyone can take the same strides, which may improve the range of measurements. 6. The total distance of the course was 1319 cm (13.19 m). 7. a. No, not all the measurements are the same, although some of them are very similar. The results varied from anywhere between 100 to 200 cm. b. The reason not all of them are the same is because the groups probably made a "random" error somewhere in their calculations. For example, one of the random errors could have been not going in a straight line, or looking at the wrong end of the meter stick (looking at the 70 cm instead of the 30 cm). Some of them were probably close because those groups probably didn't make the error. c. Another method of measuring could be to find out how big each tile in the hall way is and then find out how many tiles are in between the black strips of tape. Then you could multiply both those numbers and see how long the course is (you may have to switch the units around so it is in metric). Groups answers probably wouldn't vary that much because there really isn't a whole lot of error that could happen in this method. d. I think some of the possible values would be close to that of the values we got using the meter stick, as long as their weren't any errors with the meter stick. An example of value might be 13 meters 19 centimeters because that is what we got measuring the course with the meter stick. Not every group may get the same value because some groups may still make a systematical or random error. e. I think there will always be some difference in measurements because no matter what every person is different and may make a mistake. Even if there isn't a systematical error there may be a human error in the calculations. 8.a. Yes, one example of a systematic error that we faced was starting at the wrong point on the meter stick or tape measure. After we realized this, we changed how we used the tool and got correct measurements. b. During the meter stick measuring the random error was probably anywhere from 0-3 cm. During the tape measure measuring, the error margin was probably anywhere from 0-2 cm. 9.a. This is a good estimate because the average person probably weighs anywhere between 200 and 250 lbs when in college, with some players being under or over that mark. b. This is not a good estimate because the average fully grown person is 6 foot tall, not to mention when they are in high school. 7 feet would be considered tall never mind 13 ft. c. This is not a good estimate because if you say the average teacher works 8 hours per day that is only 480 minutes, not 1660 minutes. d. This is not a good estimate because an average poodle weighs about 40 pounds maximum (most between 20 and 30 pounds) and also, I have a Labrador and she isn't even 130 pounds and she is overweight. e.This is not a good estimate because 150 cubic meters (400+ feet) is definitely not a good approximation of the average class size. It would be more like 25 cubic feet. f. The distance across school grounds is definitely not .6 miles because that is more then half a mile and I can guarantee you the school grounds aren't even a half mile long. h. You must first estimate how big both your truck and the other guys truck is. Once you figure that out you must estimate how big the bridge is. If you estimate that both of you can get past each other then you could for it, but if not then its not worth the risk. i. I would say that both the motor home and the bicycle will get through safely because if you think about it, the maximum height of the motor home would be 15 feet (and that's on the big side) and a bike was about 3 feet tall, then that is only 18 feet tall, so that would mean you would have 3 feet to spare.

1. This difference between systematic and random errors is, systematic errors are errors that can be avoided or corrected with calculations. Random errors are errors that can not be corrected by calculation, for example, you can use a more precise measuring tool. 2. There will always be uncertainty in measurement because no matter how perfect the system of measuring is, there will always be some sort of human error. And because of that human error, you may always get different numbers then the actual answer. 3. To have no accuracy nor precision you must have all the arrows be spread out randomly, with some of them off the target.
 * Physics Talk, Checking Up-**

1. +/- 10 cm = 49.9 m--->50.1 m (difference of 20 cm) +/- 1 cm = 49.99 m---> 50.01 m (difference of 2 cm) +/- 1 mm = 49.999 m---> 50.001 (difference of 2mm) 2. speed= distance/time ---> t=distance/speed speed= 50 m/25 m= **2 m/s** t= 2cm/2 m/s = .2m/ 2m/s= .01 seconds. 3. speed= distance/time........speed=1500 m/ 900 seconds= 1.666 m/s t=60cm/1.666m/s= .6 m/ 1.666 m/s= **.360 seconds** 4. It is possible that someone broke the world record by 1/1000 of a second because the pool might be a few millimeters shorter or longer then the previous pool. These few millimeters could be the difference between a world record or not as was the case in this example question. 5. This problem of the pools in most cases
 * Active Physics Plus-**

- You can reduce random errors by making sure you are always using the right tricks and steps when using a piece of equipment. It can be one stupid mistake like using the wrong side of the meter stick to screw up a whole project, so just always take that extra second to make sure everything is being used properly.
 * What do you think now?**
 * Most likely one of the people made a mistake because that is such a big difference (about 21 feet). Chances are there was some sort of mistake, whether it be a random or systematic error, who knows, but I am sure there was some sort of mistake.
 * There most likely wasn't a mistake on this measurement, the only difference is one is more precise then the other. This could be because of the tool being used (maybe one is more precise then the other) or one of the people measuring rounded up .1.

1. a. It is best to use a centimeter ruler for the quarter and the water bottle. And it is best two use a meter stick for the table, laptop and ring stand. b. For each measurement there is a +/- 5 mm of uncertainty. 2. It takes 16 strides to walk the length of the room and 11 strides to walk the width of the room. With an average stride of about 50 cm, the length of the room would be 800 cm x 550 cm. With a meter stick the size of the room is 950 cm x 880 cm. 3. Me and my friend both estimated the same length of a pencil. We both estimated it would be about 8 inches. But, then when we estimated the height of a door, I estimated about 8 feet, but estimated it to be about 9 feet. 4. In my own estimate, I would say that this is a reasonable number, if not on the lower side. If the average cost of each barrel is $100, the total cost of all the oil would be $500,000,000. This price could be unreasonable because perhaps the barrels aren't completely full, which would decrease the value of the oil. 5. The accuracy on the labels are very accurate.This is because food companies are forced to tell the consumer the exact number of what is in the product for each of the categories (carbs, grams of fat, servings, etc.). 6. a. This estimate is right on the edge of not being appropriate, but I would say that it is still reasonable. I think each of the 12 people would be able to get a glass of the soda, although the size of the glass would be on the smaller side. Dependihttp://acp7schwarz.wikispaces.com/Chapter+1ng on whether you think the people should get two glasses of soda, then I think the estimate is unreasonable. b. This estimate is reasonable. Considering the distance between Boston and NYC is less then 300 miles, I think you would be able to make it. This is because, in my opinion, that the average midsized SUV would hold over 300 miles of gas. 7. The difference of measuring the size of your room and being off by 1 meter is different then that of measuring the distance between your house and the school and being off by 1 meter. The room is a much smaller scale measuring and therefore should be a lot more precise. Where as the distance between your house and the school could be miles and 1 meter could be saying you were off by a few millimeters when measuring your room, the difference is tiny. 8. a. To guarantee you do not go over the speed limit you should go 60 mph, this will insure that your speed range would be between 55 mph and 65 mph. b. The passenger could use the formula, speed=distance/time and measure out a mile and see how long it took and then use the formula to find out the speed. 9. You should not get a ticket for being 1 mph over the speed limit because this isn't giving the driver any leeway to stop. Also, the driver might be misreading the speedometer because the little ticks are so small and sometimes don't even exist. Because of all these disadvantages the speed limit for getting a ticket should be a minimum of 5 mph over the speed limit or maybe even 10 mph over the speed limit.
 * Essential Questions**
 * What does it mean? This type of error would be a random error. A random error affects can effect accuracy because you will be getting numbers that are way off from what you would if you were using the proper measuring tool.
 * How do you know? I know that the jeweler can not know that there is exactly 1 oz of gold because it is such an exact number. Perhaps the jeweler weighed the piece of gold and got .9789 oz. The jeweler then maybe rounded up to 1 oz just so it sounded like a better deal for the customer when in actuality the customer would be getting ripped off.
 * Why do you believe? I believe that you can not trust all experiments if they are based on measurements because during our class activities, there was not once where every group got the same, consistent answer. And because of that I feel that you can not trust that every measurement is always right. Therefore, you can not trust all experiments.
 * Why should you care? The consequence of not measuring stopping distance correctly could be fatal. Even if the stopping distance that you estimated is half a second off of the actual stopping distance, that half second could be the difference of life and death. That half a second could be the difference of barely avoiding an accident or going 60 mph into the back of a tractor trailer.
 * Physics to Go**
 * || Length ||
 * Table Width || 106.5 cm ||
 * Water || 20 cm ||
 * Laptop || 33 cm ||
 * Ring Stand || 52 cm ||
 * Quarter || 2.2 cm ||

__Section 3-__

 * What do you see?**
 * I see a car accident between 3 cars.
 * Right next to the car accident there is a rabbit on the side of the road.
 * Everyone in the cars that were in the accident are looking out the window towards the rabbit (Maybe the rabbit distracted the drivers).
 * The cars are still moving though because the lady in the yellow convertible her hair is still going back and so is the dog's ears. Also, the bunny's ears are pushed forward by the of the car which is caused by the speed of the cars.
 * What do you think?**
 * A safe following distance with your vehicle and the car in front you is the 2 second rule. This is where you pick an object and from when the vehicle in front of you crosses that object, you make sure you don't pass that object in 2 seconds.

b. No, the automobiles are not the same size apart successive photos. The images are farther apart then they were at 30 mi/h. The car going 30 mi/h goes .5 miles in 1 hour. And the car that is going 45 mi/h goes .75 miles in 1 hour. c. I decided how far apart each of the x's would be by putting 60 spaces in between each of them. Same thing for the above. For 45 mi/h I put 45 spaces and the one for 30 mi/h I put 30 spaces.
 * Investigate**



b. Yes, each vehicle is traveling at a constant speed. You can tell this because they all have the same spacing in between each of the cars.

4a.

b.

c.

d. 5a.

b. 6a. b. 7a. According to the graph on 5b (our most recent chart as of now) we walked 2.55 meters, which is 1.25 meters toward the motion sensor and 1.3 meters away from the motion sensor. b. It took the person walking 4.94 seconds to walk this distance. The difference between the finish and the start is 6.5 seconds minus 1.56 seconds which gives you 4.94 seconds. c. 1.25m/4.94 seconds= .253 m/s. d. My assumption would be that the position of the person that is walking twice as long would be twice as far from the original number. This makes sense because you are doubling the position from the first trial by the new one. 8a. If the person's reaction time is .5 seconds that means the car will have traveled 30 feet in those .5 seconds. I know this because if the car is going 60 feet per second that means it is going 30 feet in .5 seconds. b. If the person's reaction time is 1.5 seconds I can do the same things as in 8a to determine how far the car will travel. I know that the car is going 60 feet per second, so the car will travel 90 feet in 1.5 seconds. c. If the car is going 50 feet per second then the car will travel 25 feet. And if the person's reaction time is 1.5 seconds the car will travel 75 feet. d. If the car is going 70 second and the person's reaction time is .5 seconds, the car will travel 35 feet. And if the person's reaction time is 1.5 seconds the car will travel 105 feet. e. If the car is traveling at 40 feet per second and the driver has a reaction time of .5 seconds, to avoid hitting the car, the preceding car should travel at at least 20 feet per second to allow the person to stop just short. f. An automobile traveling at 60 feet per second travels about 4 car lengths per second if the average car length is 15 feet.


 * Physics Talk-**

Time= distance/Vavg Distance= time*velocity

1a. b. 2a. b. 3.
 * Physics Plus-**


 * What do you think now?**
 * A safe following distance for your automobile and the vehicle in front of you really depends on the speed of your car. I think the faster your car is going the more space you should allow. The average following distance should be 3 seconds.
 * You can find this by using the formula Vavg= distance/time. But, you can move this equation around to better find out your following distance by doing: distance= time*Vavg. The numbers you plug in should be 3 seconds for time and your average velocity in units/second. And by solving this equation you could find your following distance.
 * Essential Questions-**
 * What does it mean? This means that the car is traveling 40 miles/hour. This means that in 2 hours the car could travel 80 miles.

1a. In this strobe photo the car is moving at a constant speed. b. In this photo the car is moving at a constant speed but then speeds up quick and goes back to the constant speed. I know this because the car has the same spacing, then the spacing gets larger and then it goes back to the equal spacing. 2a.
 * Physics To Go**-

b.

3. Distance= time*Vavg D= 350 ft/s * 20 seconds= **7000 feet** 4a. Vavg= distance/time========> Vavg=215 miles/ 4.5 hours= **47.777 miles per hour.** b. No, you do not know how fast they were going through Baltimore because maybe they were in traffic because they may have been in traffic. 5. Vavg= distance/time=========> Vavg= 5 miles/ .25 hours= **20 miles per hour.** 6a. In this graph the car is driving at a constant speed and then it comes to a stop b. In this graph the car is maintaining a constant speed going away and then comes to a stop. After it comes to a stop it maintains a constant speed going toward the object at a lesser velocity then when it was driving away from the object. c. In this graph the car is driving at a constant speed and then accelerates to a faster speed which it maintains. d. In this graph the car is continuing its acceleration without slowing down. 7a. distance= time*Vavg=====> distance= 25 m/s* .12 seconds= **3 meters.** b. distance= time *Vavg=====> distance= 16 m/s* .12 seconds= **1.92 meters.** This distance is a less distance then that of 25 m/s. This is because the car is going at a slower speed, which increases my reaction speed. c. distacne= time*Vavg=====>distance= 25 m/s* .24 seconds= **6 meters.** 8a. Traffic experts can determine this time by using the formula distance= time*Vavg. You can do this by multiplying your speed of your car by 3 seconds and this distance you get should be the space you leave between the car in front of you and yourself. b. No, three seconds on an interstate or rural road probably won't be enough time because you are traveling at a higher rate of speed, which means the distance you travel after you stop would be greater which could cause an accident. 9a. distance= time*Vavg ======> distance= 100 ft/s * (1/3) second= 33.333333 feet. b. Yes, this is longer then the length of the classroom. 10a. distance= time*Vavg =====> distance= .5 seconds* 88 feet/second= 44 feet. b. This space can fit 2 cars and almost 3. If there was one more foot in the space you can fit 3 cars. c. distance= time*Vavg =====> distance= 43.8 feet/s* .5= 21. 9 feet. You can fit just one car in between the space. d. distance= time*Vavg =====> distance= 132 feet/s *.5= 66 feet. This is 4.45 of a football field. I know this because 300 feet/ 66 feet= 4.45. e. At each of these increasing velocities, the person's reaction time is getting slower and slower. For example at 30 mph to 60 mph the person's reaction time doubles and from 30 mph to 90 mph, the person's reaction time triples. 11.

__Section 4-__
1a. I think that the farther the car gets down the ramp, the faster the car will go. b. The chart in which one of them does not move is the chart on the bottom right. A chart in which the more time goes by the farther the car goes is the chart on the top right.The chart in which the car travels at a constant speed is the car on the bottom left. And the chart in which the car travels fastest at the end is on the top left. c. In this graph the car will start off moving slowly down the ramp and at time goes on and the distance increases the faster the car will be going. 2a. b. The graphs from our prediction and that of the actual graph are very similar and there really aren't any differences. c. In the examples only A and B are tangent lines, but C is not. An example of a tangent line for C is: d. As time increases the slope will continue to increase because the car will continue to gain speed. e.
 * What do you see?**
 * I see a guy and his dog running across the street in front of a person driving in a red car.
 * The person driving has a green light so they are probably accelerating.
 * Mean while the person driving the yellow car also has a green light but she is letting the guy and his dog cross.
 * What do you think?**
 * Some of the similarities would be that they both start at the same speed of 0 mph (initial velocity) and they both reach the same speed of 30 mph (final velocity). They are both accelerating (going forward).
 * Some of the difference would be that the car would take less time for the person driving the car to reach 30 mph then the bus. Also, it will take longer for the bus to come to a stop.
 * Investigate-**

3a.

b. Compared to 2e the prediction and the actual graph are pretty similar because they both start at 0 and gradually increase in velocity. The graph starts at (0,0) because when the car is at rest it is not moving and therefore has no velocity. c. The change in the slope as time increases will be equal because the car has a constant velocity. d. The acceleration of a car as it travels down the ramp is constant. e. acceleration= change in velocity/change in time =======> acceleration= .5-.35/1.60-1.35 =======> acceleration= .15/.25= .6 m/s^2.

4a. b. 5a. b. c. The slope of the d-t graph is negative when the car is going up the ramp and positive when the car is going down the ramp. This is because when the car is going up the ramp the car is losing speed, but when the car is going down the ramp it is gaining speed. d. The slope of the v-t graph is negative when the car is going up the ramp and positive when the car is going down the ramp, just like in the d-t graph. This is because when the car is going down the ramp the car is losing velocity and when the car is going up the ramp it is gaining velocity. e. The slope of the car going up the ramp in the d-t graph is -.325. This means the car has a negative acceleration of -.325 meters/second. And the slope of the car going down the ramp is .741. This means the car has a positive acceleration of .741. The slope of the car going down the ramp in the v-t graph is -3.22. This means the car has a negative acceleration of -3.22 meters/second. The car going down the ramp in the v-t graph has a slope of .85. This means the car has a positive acceleration of .85 meters/second. 6a. The d-t graph will look like this because as time went on the distance increased, but the slope of the line started decreasing because as the car went up the ramp the speed of the car will continue to decrease. b.The v-t graph will look like this because as the car goes up the ramp the velocity at first is fast but as time goes on the car's velocity will decrease because the car's speed is slowing down. 7a. b. The prediction of what the d-t graph would look like from 6a is very similar to what the actual d-t graph looked like. There really isn't any differences. However there is a minor difference in the prediction of what the v-t graph would look like (6b) and what the actual graph looked like. On our prediction we had the graph being a more steep decline compared to the actual graph where it is a more gradual decline. c. The slope of the d-t graph is pretty constant as it increases, but towards the end of the acceleration it starts to round off. The reason for this is because the car is starting to slow down and is about to turn around because it can no longer continue up the ramp. d. The slope of the v-t graph is also fairly constant at first, but then the slope starts to decrease to the point where it is a negative slope. The reason for this is because as time goes on the velocity of the car continues to decrease. e. 8a. In order to get this graph the motion sensor and the car would both need to be at the top of the ramp facing down to the bottom of the ramp. When you release the car you will get this graph because the car will gradually pick up speed as it continues down the ramp. b.In order to get this graph both the motion sensor and the car would need to be at the bottom of the ramp facing towards the top of the ramp. When you push the car up the ramp the car will start with a higher velocity, which will start to decline as it gets farther up the ramp to the point where it falls back down. This chart represents the area of the car going up the ramp to the point where the car starts to slow down. c. In order to get this chart the motion sensor and the car would be set up at the top of the ramp. In order to get this kind of line the car would need to increase its speed down the ramp. You know this because as time goes on in this chart the velocity of the car is also increasing. d. In order to get this graph the car could be at the bottom of the ramp, but the motion sensor will be at the top of the ramp. When the car is pushed up the ramp towards the motion sensor you should get this graph because the car's velocity will decrease as time goes on. 9a. (This chart is not in this section). 11a. b. From 0 seconds to 2.9 seconds the velocity is changing the most. c. From 4.2 seconds to 13.3 seconds the velocity is changing the least. d. The acceleration is greatest at 2 seconds because the change of 44 ft/s and 0 f/s is 44. But, the acceleration is the least at both 4.2 seconds and 8.7 seconds. At both of these time periods the change in velocity is 14 ft/s, meanwhile everywhere else on the chart (except for at 2 seconds) the change in velocity is 15 seconds. 12a. acceleration= change in velocity/ change in time ========> acceleration = 59 feet per sec- 44 feet per sec/ .9 seconds= 16.667 ft/s^2. Yes, I got the value of 16 ft/s for every second. b. c. The steepest incline (greatest slope) according to the chart is the same as what I predicted according to the velocity-time graph from question 10a. Both indicate the steepest incline is at 2 seconds.

- Velocity is how fast an object is going and in what direction, therefore velocity is a **vector** quantity. - Vector means to be both size and direction. - The distinction of speed and velocity is important when a change in direction happens because when a car is going around a curve at a constant 15 m/s the car is still accelerating because there is a change in direction. - The three ways you can increase a cars velocity are: - Instead of using deceleration a person should use the terms **positive acceleration** or **negative acceleration** to avoid confusion. - When an object has mass (speed) but no direction the term used to describe it is a scalar quantity. - acceleration= change in velocity / change in time. - The unit for using acceleration is m/s^2 or (m/s)s. - Some other key formulas are: - To show acceleration by graphing you would need distance on the y-axis and time on the x-axis. You would then need to put in the tangent line in and find the slope of the graph. That line is the acceleration.
 * Physics Talk-**
 * -** Galileo was the person who invented the idea of acceleration. He did this by rolling balls down an incline and used things such as a water clock to help him track the time that elapsed. He presented the idea that acceleration is equal to the change in velocity over the change in time.
 * Increase the speed (speed up)
 * Decrease the speed (slow down)
 * Change the direction of a car (turn)
 * Change in velocity= acceleration * time
 * time= change in velocity / time


 * Motion Equations-**
 * Homework 10/17- Average Acceleration/ Displacement With Constant Uniform Acceleration/ Velocity and Displacement with Uniform Acceleration:**

1. Yes because acceleration is equal to change in velocity / change in time. So, as long as the velocity is not changing then the acceleration would be zero. 2. Yes, because say you throw a ball in the air. When the ball reaches its highest point the ball comes to a stop for a very small period of time. But, even during this time period, gravity (9.8 m/s^2) is still acting upon it. 3. Yes because we know that V= acceleration * time. If the object has the same acceleration there is no amount of time that you can multiply by to get a different velocity, which proves the idea wrong. Say two objects have the same acceleration of 5 m/s^2 but one it is over 1 second, but for the other object it is over 2 seconds time, you will get different velocities. 4. Yes, a car with a constant velocity would be able to overtake a car that is accelerating because if the car just started its acceleration it would be going slow and the car with a constant velocity would be able to pass it. 5. No, because even if the car with the constant velocity has a head start, it won't be able to hold the lead for ever. Because the car is traveling at a constant velocity, there is no acceleration, which means the car isn't gaining any ground on the car, in fact, it is losing ground. Because the other car is accelerating, that means its velocity is also increasing. This means that even if the car started off behind the car not accelerating eventually it will catch up with the car and take the lead and not lose it. 6. It does matter because speed limit signs only refer to the speed of the car. Whereas the velocity limit signs would refer to speed and direction. The unit used to measure speed in the US is miles per hour. 7a. V= acceleration * time. V= .0005556 mi/second * 5 seconds= .00278 mi/second. b. distance= 1/2 (Vinitial + Vfinal) * change in time ========> distance= 1/2 (0+.003)*120 seconds= .36 miles/second. 8a. acceleration= change in velocity/ change in time ======> acceleration= 75 m/s / 9 seconds= 8.33 m/s^2. b. Vavg= (Vi+Vf)/2 ========> Vavg= 0+75/2= 35 m/s. c. distance= 1/2 (Vi+Vf) * time =====> distance= 1/2 (74.997+0)*9= 337.49 meters. d. The second cars acceleration would be greater then that of the first car. The second cars average speed during the acceleration would be greater then that of the first car. And the distance traveled would be less then that of the first car. 9a. acceleration= change in velocity/change in time ========> acceleration= .6-4.5/1.3= -3 m/s^2. b. distance= 1/2 (Vi+Vf)*time =======> distance= 1/2 (5.1)*1.3= 3.315 meters. c. Vavg= acceleration * time =======> Vavg= -3 * 1.1= -3.3 m/s. d. The first trial would get her from second to third the fastest. 10a. The approximate top speed reached by the object falling was about 11 m/s. b. acceleration= change in velocity/change in time ========> acceleration= 9/7.5= 1.2 m/s^2. The acceleration of gravity on this planet is 1.2 m/s^2. c. If the astronaut dropped the object from a higher point, then the acceleration would not change, but the objects final velocity would increase. 11a. Graph "B". b. Graph "D". c. Graph "B". d. Graph "A". e. Graph "F". f. Graph "E". 12a. b-e b. a-c c. d-e d. e-g e. 0 meters f. 0 meters 14a. b. c. d. e.
 * Part 1:**
 * Part 2:**
 * Part 3:**
 * Physics to Go:**

__Section 5-__

 * What do you see?**
 * I see a person that is stopping short of a moose trying to avoid hitting it.
 * The smoke coming out from under the tires shows me that the car is stopping.
 * The wooded area behind the moose is probably where the moose is coming from.
 * The person didn't try swerving to avoid hitting the moose, but instead only breaking.
 * The driver is really trying to break with all of his power to stop the car. You know this because his body is pushing all the way back in his seat and squeezing the wheel to avoid from taking his hands off the wheel.
 * What do you think?**
 * Things like slick road surfaces or snow or ice on the road will slow down the amount of time to stop the car because the tires might slide.
 * If there is any cars behind you.
 * Your reaction time.
 * Your speed.
 * If the animal is moving and if so, what direction.

1a. b. It would look like this because as the speed of the car increases then the breaking distance would also increase. But, if the car was going at a slower speed, then the breaking distance would be smaller. 4a. 5a. b. As the initial speed increases so does the breaking distance. c. Compared to our prediction of what the graph would look like, the actual graph is somewhat similar. They are similar in the fact that as the velocity initial increases, so does the breaking distance. But, in our prediction, the breaking distance keeps increasing at a faster rate, whereas in the actual graph it increases at a much slower rate. d. (Can't Compare to other groups) e. (Can't Compare to other groups) 6a. In one of our trials the initial speed was .995 m/s with a breaking distance of 1.28 m. And in another run it was 1.899 m/s with a breaking distance of 3 m. With the initial speed almost exactly doubled, the breaking distances vary. When the car had a double the initial speed of the other car, its breaking distance was more then 2x as much as half of its initial speed. 7a. Because we don't have initial speeds that are exactly 3x as different, we will use numbers that are most similar to it being 3x as much. One of our initial speeds were .892 m/s and its breaking distance was .90 m. While another cars initial speed was 1.899 m/s and had a breaking distance of 3 m. With the difference in initial speeds 2.13 as fast as the other one. The breaking distance for the car that is going 2.13x faster then the other car is more then 2x faster then the original car's breaking distance. b. Going 4x faster then the initial speed would increase the breaking distance by more then 4x as well. 8a. The breaking distance is found on the first page right under the fuel economy section. b. No, I do not expect the ratio of the breaking distances to be in the same ration of 80/60=1.33 because I think the breaking distances will have some difference. The actual ratio of the breaking distance is 228/135= 1.6889 or 168.89%. This is a little bit greater then the ratio of the two speeds. c. This compares to our data in the fact that it is similar in some instances, but different in others. For some of our breaking distances there are increases of 107%, 142% or 154%. Some of the numbers are close to that of 169%, but others aren't even close.
 * Investigate-**
 * || Velocity Initial || Distance Traveled ||
 * Trial 1 || 1.899 || 3.00 m ||
 * Trial 2 || 1.814 || 2.78 m ||
 * Trial 3 || 1.149 || 2.23 m ||
 * Trial 4 || 1.635 || 1.98 m ||
 * Trial 5 || 1.285 || 1.89 m ||
 * Trial 6 || .995 || 1.28 m ||
 * Trial 7 || .892 || .90 m ||
 * Average || 1.381 || 2.01 m ||


 * Motion Equations-**
 * Motion Equation #5 Practice Problems (HOMEWORK)**


 * What do you think now?**
 * Your initial velocity.
 * The acceleration of the car.
 * Quality of the car's breaks.
 * Road Conditions.

1. This means that as the velocity of the car increases, then so does the breaking distance. This is related to safe driving because the driver must know that the faster the car is going the longer it will take to brake. 2. You know this because the square velocity of the car (in this case 3) is equal to the breaking distance (in this case 9). 3. Positive acceleration is when the car is speeding up, but negative acceleration is when the car is slowing down. 4. Knowing the relationship between breaking distance and speed lets a driver know that the faster the car is going, then the longer it will take to brake. Knowing this lets the driver get a heads up that the faster they are going, they need to break sooner because it will allow the driver to start braking in time to let the car stop. 1. As the initial velocity increases, so does the breaking distance. Also, as the initial velocity doubles the breaking distance nearly quadruples. 2. In this example, Automobile A is safer. I know this because as the velocity continues to increase, the breaking distance for Automobile A is consistently shorter then that of Automobile B. In this question I assumed the word "safer" meant a shorter breaking distance. 3. a. 20m/30mi/h = x/15mi/h x=10m. If a car is able to stop in 20 meters at a speed of 30 miles per hour, then the car would be able to stop 10 meters while going at 15mi/hr. b. 20m/30mi/h = x/60mi/h x=40meters If a car is able to stop in 20 meters at a speed of 30 miles per hour, then the car would be able to stop in 40 meters while going 60mi/hr. c.20m/30mi/h = x/45mi/h x=30m. If a car is able to stop in 20 meters at a speed of 30 miles per hour, then the car would be able to stop in 30 meters while going 45 mi/hr. d. 20m/30mi/hr = x/75mi/hr x=50m. If a car is able to stop in 20 meters at a speed of 30 miles per hour, then the car would be able to stop in 50 meters while going 75 mi/hr. 4. x=1/2 (Vf + Vi)* T x= 1/2 (0+10)*.9 x= 4.5 m + 30 m= **34.5 meters** 5. 60 mph: 118 ft 30mph: **59 ft** 6. Breaking Distance at 50 mi/h: 60 mi/h: 135 ft 50 mi/h: **112.5 ft** Breaking Distance at 25 mi/h: 60 mi/h: 135 ft 25 mi/h: **56.25 ft** Graph: 7. With reaction time, the driver of the sedan would stop in 140 meters.
 * Physics Essential Questions-**
 * Physics to Go-**

__Section 6__-
GO ZONE= velocity of the car * yellow light time - width of intersection STOP ZONE= VTr + V^2/2a
 * Learning Outcomes-**
 * Investigate the factors of the stopping distance of the "stop and go" zones.


 * What do you see?**
 * I see a car (the red one) skidding trying to stop at the light.
 * I see another car (the green one) just driving through the light, not slowing down.
 * The light where the cars are going through is red, but it is green going the other way.
 * There is a cop on the sidewalk so maybe the red car was trying to stop short and prevent running the light.
 * The green car is definitely accelerating.


 * What do you think?**
 * I think that if all traffic lights stayed yellow for the same amount of time, it would help the driver make up their decision at the intersection a lot quicker. This is because if the driver is approaching the intersection at 5 seconds then maybe they will start to break because they know the red light is coming up. But, the same is true that if they knew when the light was turning red and they wouldn't have time to stop then they can speed up through the light.
 * An intersection with the traffic light could be dangerous because people can become too dependent on the light and say there was a malfunction with the light, the drivers might get confused.
 * The light gives people a false sense of security and they won't check both ways before crossing.

3a. Yes, because automobile A is in the go zone and because automobile B is in front of Automobile A it will be able to make it through. b. Yes it is in the go zone, because automobile A is in the go zone and because automobile B is in front of Automobile A it will be able to make it through. c. Yes. d. Chances are Automobile C is not in the go zone. If they do decide to continue they might run the red light and end up getting hit by a car coming from the opposite direction. 4a. Yes it is in the stop zone because it is behind automobile D, which is also in the stop zone. b. No, Automobile F is not in the stop zone, but instead in the go zone. If the automobile decides to stop, it might end up in the middle of the intersection meaning they would have to go through the light anyway. c. 5a. b.
 * Investigate-**
 * **CAR** || **STOP ZONE** || **GO ZONE** ||
 * A || NO || YES ||
 * B || NO || YES ||
 * C || YES || NO ||
 * D || NO || YES ||
 * E || YES || NO ||
 * F || NO || YES ||
 * ** Variable ** || ** Change ** ||  || ** Predicted effect of change **
 * on GO ZONE ** || ** Actual effect of change **
 * on GO ZONE ** ||
 * ty || Yellow-light time || increase ty || The go zone will increase. || The go zone will increase. ||
 * ||  || decrease ty || The go zone will decrease. || The go zone will decrease. ||
 * tr || Response time || increase tr || The go zone will increase. || The go zone will not change. ||
 * ||  || decrease tr || The go zone will decrease. || The go zone will not change. ||
 * v || Speed limit || increase v || The go zone will increase. ||  ||
 * ||  || decrease v || The go zone will decrease. ||   ||
 * a || Negative acceleration || increase a || The go zone will decrease. || The go zone will not change. ||
 * ||  || decrease a || The go zone will decrease. || The go zone will not change. ||
 * w || Width of intersection || increase w || The go zone will increase. || The go zone decreases. ||
 * ||  || decrease w || The go zone will decrease. || The go zone increases. ||

6a. The go zone at 3 seconds would be 53 meters. b. The go zone at 3.5s would be 63 meters, which is 10 meters farther then that of when it was 3s. c. Yes it would because as the yellow light time increases then so does the amount of time (distance) the person has to get to and through the intersection safely. d. The effect of changing the yellow-light time is that if the amount of time the yellow-light is up for increases, then more people can get through the intersection safely. But, if the yellow-light time decreases, less cars will get through the intersection safely.

8a. yellow light time: Yes this makes sense to us. human reaction time: This does make sense to us, although our prediction was off. We predicted that the go zone will increase, but in fact it did not change. negative acceleration: This does not make sense to us because as the car slows down, then why doesn't the go zone decrease because the car isn't driving fast enough to make the light. width of intersection: This does not make sense to use either because the width of the intersection should mean that the wider the road the more cars get through, not less of a go zone. b. Our prediction for yellow-light time in relation to the go zone is right on, but all of the other predictions were off. c. Go zone= velocity of the car * yellow light time - width of intersection. d. These three factors appear in the equation because they are the only factors that effect the go zone. e. These two factors do not appear in the equation for the go zone because they have no effect on the go zone. They do not have an effect on the go zone because they do not have any effect on the go zone. When you are in the go zone, the reaction time has no effect on driving with a constant speed.

9a. STOP ZONE= speed of vehicle * human response time + speed of vehicle^2 / (2* negative acceleration rate). b. They do not relate to the equation for stop zone because they have no effect on the stop zone. Those factors only effect the go zone. c. These all appear in the equation for a stop zone because they effect the stop zone. The others do not effect the stop zone because the yellow light time doesn't effect how long it will take you to stop and neither does the width of the intersection.

1a. Automobile A- Stop Automobile B- Go Automobile C- Go Automobile D- Stop 2a. Automobile E- Stop Automobile F- Stop Automobile H- Stop if possible, but it is not necessary Automobile G- Go 3a. Automobile J- Stop Automobile L- Stop Automobile M- Go Automobile K- Go 4a. Intersection II has a greater GO ZONE then the other two intersections, but the GO ZONE also overlaps with the STOP ZONE so it depends on what the other cars are doing. Also, Intersection II is the only intersection where the GO and STOP ZONES overlap. b. If you were caught in between when the light changed yellow, your choices would be to either stop or to keep going. The safest bet would probably be to keep going because the car in front of you would also be going and that way you don't have to worry about the car behind you rear-ending you. c. If you were caught in the middle of the GO and STOP ZONES in Intersection III you would have the choice of either stopping or going. In this case the best choice would probably be to stop because even though you aren't in the STOP ZONE, it is important to know that you are not in the GO ZONE either. d. Intersection II has an overlap zone. And Intersection III has a dilemma zone.
 * Section 6: Part B-**

5. a. If a car is driving at 25 mph and they are 20 feet away from the light, then it would be safe for them to go through the light. b. If a car was driving 30 mph and was 30 feet away from the light then there is no doubt in my mind they would make the light. This is because the light was designed for a car going slower then this one at a farther distance to make the light safely and because it is moving faster and is closer to the light it should make it. c. If a car was driving 25 mph and was 40 feet away from the light, chances are it would make the light safely. Although it is in the dilemma zone, it is the beginning of the dilemma zone. SO, as long as there aren't cars driving under the speed limit in front of him, he should make the light. d. If a car was driving 20 mph and was 10 feet away from the light, then chances are they could make the light. This is because even though they are going 5 mph under the speed limit they are also 23 feet under the maximum safe zone making it extra safe for them to make the light in time. e. If a car was driving at 25 mph and was 50 feet from the light this would be a tough choice for the driver. This is because he is going the speed limit but is in the dilemma zone. Even though the safe choice would be for him to stop at the light, if that was not an option he could probably make it through the yellow light in time because he is under half way through the dilemma zone. If he was 5 feet further from the light, I would not recommend him going through the light. f. If a car was driving 22 mph and were 33 feet away from the light, chances are it would not be safe for them to go through the light because, at 33 feet a car driving 25 mph could make the light safely. So, chances are if they were going under the speed limit they would not make the light in time. g. If the car was driving 25 mph and was 75 feet away from the light, the car should stop because there is no way they will make it through the light. h. If the car was driving 25 mph and was 60 feet away from the light, even though it was in the dilemma zone, I would not recommend the car keep moving. Because it is closer to the STOP ZONE then it is the GO ZONE, I would recommend it stop as long as it could. i. If the car was driving 20 mph and was 40 feet away from the light, chances are it is not safe for the driver to go. Because the car is in the dilemma zone and is going under the speed limit there is a good chance that if they try making it through the light, it won't be safe. j. If the car is driving at 40 mph and was 69 feet away from the light chances are it won't make the light in time. Even though the car is speeding 15 mph over the speed limit, they are still in the STOP ZONE and should not risk making the light.
 * **Variables** ||  ||   ||
 * Yellow Light Time (Ty) || 3 seconds ||  ||
 * Human Response Time (Tr) || .20 seconds ||  ||
 * Velocity of a Car (v) || 25 mph ||  ||
 * Acceleration of a Car (a) || 4.9 m/s^2 ||  ||
 * Width of Road (w) || 42 ft ||  ||
 * GO ZONE || 33 meters ||  ||
 * SAFE ZONE || 68.7755 meters ||  ||
 * Safe / Not Safe || It is a dilemma zone ||  ||
 * SCENARIOS** (A-E are for safe situations and F-J are for unsafe situations)
 * SCENARIOS** (A-E are for safe situations and F-J are for unsafe situations)

6a. b. widths north-south (crossing Piermont)= 40 feet widths east-west (crossing Kinderkamack)= 30 feet c. I used these numbers because then there is no dilemma zone making the intersection especially safe. In this case both roads have overlap zones and no dilemma zones, so these numbers would work fine.
 * **Variables** || **Crossing Piermont** || **Crossing Kinderkamack** ||
 * Yellow Light Time (Ty) || 3 seconds || 3 seconds ||
 * Human Response Time (Tr) || .20 seconds || .20 seconds ||
 * Velocity of a Car (v) || 35 mph or 15.64 m/s || 35 mph or 15.64 m/s ||
 * Acceleration of Car (a) || 4.9 m/s^2 || 4.9 m/s^2 ||
 * Width of Road (w) || 40 feet or 12.19 m || 30 feet or 9.14 m ||
 * GO ZONE || 34.73 m || 37.78 m ||
 * STOP ZONE || 28.0882 m || 24.0882 m ||
 * Safe/Not Safe || Overlap Zone || Overlap Zone ||


 * Physics Essential Question-**

What does it mean? How do you know?
 * Yellow Light Time
 * Width of Intersection
 * Velocity of Car
 * Reaction Time
 * Persons reaction time
 * You can measure the length of a yellow light time in our area and see if the intersection is safe. This will prove if the equation works.

1a. GO ZONE= (15 m/s)*(4 seconds)- 15 meters= **45 meters** b. STOP ZONE= (15 m/s)* (1 second) + (15 m/s)^2 / 2(5 m/s/s) = **37.5 meters** c. 2a. GO ZONE= (30 m/s)*(4 seconds)- 15 meters= **105 meters** STOP ZONE= (30 m/s)* (1 second) + (30 m/s)^2 / 2(5 m/s/s) = **120 meters** This could be dangerous because by speeding there is now a dilemma zone. b. GO ZONE= (10 m/s)*(4 seconds)- 15 meters= **25 meters** STOP ZONE= (10 m/s)* (1 second) + (10 m/s)^2 / 2(5 m/s/s) = **20 meters** By lowering the speed limit, the only effect they are making is decreasing the size of the GO and STOP ZONE'S. The intersection will still be a dilemma free zone because it is an overlap zone. 3. A person listening to loud music, which increases their reaction time does not increase the GO ZONE because while you are driving through an intersection, your reaction time doesn't matter because you aren't stopping. However, the higher reaction time effects the STOP ZONE because you need your reaction time to move your foot from the gas to the break and that increased time also increases the STOP ZONE. 4. No, this will not effect the GO ZONE and STOP ZONE at a yellow light because it is not one of the factors that effect it. The only factors that have an influence on the GO ZONE or the STOP ZONE are yellow light time, human reaction time, velocity of the car, width of the road and the acceleration of the car. 5. The reason for this is because perhaps up the road there is another light and the time that the light does not turn green is to keep traffic flowing normally, without traffic. The time in between red and green lights could let the traffic up the road clear before more traffic comes. 6. Traffic engineers probably don't use this now because even though the light was yellow, cars can still go through the light. It might make more sense if they did this countdown to the red light to help drivers judge the yellow light time. The countdown effects the stop and go zones because people might speed up their car to try and force their way through the light, which in turn could decrease the size of the go zone and stop zone as well as cause a dilemma zone, which might make the intersection unsafe. 7. A- GO: 48 m STOP: 52.57 m This is unsafe because there is a dilemma zone of 4.57 m. B- GO: 72 m STOP: 52.57 m This area is a safe zone because there is an overlap zone that is 19.43 m. C- GO: 48 m STOP: 48.57 m This area is unsafe because there is a slight dilemma zone that is .57 meters long. D- GO: 48 m STOP: 64.57 m This area is unsafe because there is a dilemma zone that is 16.57 meters long. E- GO: 40.5 m STOP: 34.07 m This area is safe because there is an overlap zone that is 6.43 meters long. 8. Yes, because then there is no doubt in people's minds if they would be able to make the yellow light or not. This would probably count down on the number of lights and tickets that might occur at intersections. 9. Dear Mom and Dad, I think you should let me use your car because during this section I have learned everything I need to know about intersections with a yellow light. I have learned that if you are in a certain area called a go zone, then it would be safe for me to make it through the yellow light. Contrary to this though, if you are in a stop zone, it is unsafe to make it through the light and you should stop. The area in between the two could either be a dilemma zone or overlap zone. If it is a dilemma zone, then you must make a decision based on the other cars behind you and in front of you. This area is dangerous because either way you go, it is not guaranteed if you could stop at the light in time or guaranteed that you can make it through the light in time. But, the dilemma zone is a rare occurrence because most intersections are overlap zones. In this area the driver could either chose to go or stop and it would be safe either way.
 * Physics To Go-**

__Section 7-__

 * Learning Outcomes-**
 * Recognizing the need of centripetal force as you are rounding a turn.
 * Predict the effect on an inadequate centripetal force.
 * Relate speed to centripetal force.
 * What do you see?**
 * I see a car that is going around a bend on a mountain.
 * It looks as if the car is about to go off the side of the mountain.
 * This is because you could see the sign on the side of the road that got hit and is falling off the cliff.
 * It doesn't look like the driver ever had control of the car because the smoke path left by the car is all over the place.
 * Perhaps the car was going too fast around the bend that they ended up going over the edge while turning.
 * What do you think?**
 * The sign is indicating to slow down because if you are going to fast around the bend then it could be potentially dangerous because you could lose control of the car when turning.
 * The amount you slow down by is probably determined by things like:
 * How wide the road is
 * What the previous speed limit was
 * How dangerous the road is (like in the picture there is a cliff which makes it more dangerous)
 * What the road condition is (ice, snow, sleet, etc.)

Equations for circular motion:





Equations for friction: or F= mv^2/ r


 * How are these equations used when driving?**
 * Circulation motion is used when driving because in order to move any direction there needs to be a force applied. If there is no force applied, the car will keep moving straight. This is Newton's First Law of Motion.

1a. B, because as you take your finger off the string the car will not have any force making it go in the circle anymore. So, without the force making it go in the circle, the car will go straight. 2a. The direction of force being applied on the car is pulling it towards the center. b. When the string is released, the car continues traveling in a straight line. 3a.
 * Investigate-**

4a. It is 19 cm to the center of the turn table. 6a. 17.29 seconds for 10 revolutions. b. 10 revolutions/17.29 seconds= x revolutions/ 60 seconds 17.29x=600 x= 34.7 revolutions per minute (rpm) c. 34.7 revolutions/ 60 seconds= x revolutions/ 1 second 60x=34.7 x= .578 revolutions per second (rps) d. This is a better technique because this way you get a wider field of measurements and find the average instead of just using one time. By doing it the way we are we are getting a more reliable time. e. The turntable is moving at .578 revolutions per second (rps). 7. The circumference of the circle is equal to 2(pi)(r) So, c= 2(3.14)(19)=119.32 cm a. Speed= distance/time Speed= 1.1932 m/ 1.729 seconds Speed= .69 m/s 4a. It is 19 cm to the center of the turntable. 6a. 10.90 seconds for 10 revolutions. b. 10 revolutions/10.90 seconds= x revolutions/ 60 seconds 10.90x=600 x= 55.04 revolutions per minute (rpm) c. 55.04 revolutions/ 60 seconds= x revolutions/ 1 second 60x=55.04 x= .917 revolutions per second (rps) d. This is a better technique because this way you get a wider field of measurements and find the average instead of just using one time. By doing it the way we are we are getting a more reliable time. e. The turntable is moving at .917 revolutions per second (rps). 7a. Speed= distance/time Speed= 1.1932 m/ .917 seconds Speed= 1.3 m/s
 * FOR A LARGE WASHER ON A SMOOTH SURFACE**
 * FOR A LARGE WASHER ON SANDPAPER**

8a. The effect that sandpaper will have on the washer is that the washer will have better traction and therefore will be able to stay on the turntable longer. 9a. The smaller the radius is, then the greater the safe speed of the car will be. b. (s) || Time of 1 rev (s) || Time of 1 rev (s) || Average Time of 1 rev (s) || Circumference (cm) || Maximum Safe Speed (m/s) || d. As the radius decreases the maximum safe speed decreases as well. 10a. The heavier the truck is then the faster it would be able to move through a curve. b. c=2(pi)(r) c=2(3.14)(19) speed= distance/time speed= 119.32/1.368 speed= 87.2 m/s Velocity of the heavier disk: 81.33 m/s Velocity of the lighter disk: 87.2 m/s c. Yes, because of the demonstration we did using the turntables we found that the heavier car can move through the turn at a quicker speed because there is more weight holding the car down, which means there is less likely a chance that it will flip or fall off.
 * Radius (cm) || Time of 1 rev
 * 19 cm || 1.602 || 1.366 || 1.433 || 1.467 || 119.32 || 81.33 m/s ||
 * 10 cm || 1.330 || 1.220 || 1.358 || 1.302 || 62.8 || 48.23 m/s ||
 * 5 cm || 1.182 || 1.124 || 1.152 || 1.153 || 31.4 || 27.23 m/s ||
 * circumference**=119.32
 * time**=1.368 seconds
 * speed**=?


 * Physics Talk Outline-**
 * Newton's First Law of Motion- an object in motion will continue to stay in motion in a straight path and constant speed unless an outside force acts upon it.
 * During the investigate the outside force that acted upon the car was the string that made it curve.
 * If any car is turning or curving, you know there is a force acting upon the car making it do this.
 * The force of friction is always toward the center of the circle.
 * We saw this when the string was pulling on the car, it was pulling to the center.
 * Or when the block was on the turntable, that friction between the two was pulling to the center.
 * When driving an automobile the friction between the tires and the road keeps the car's ability to move in a circle.
 * The force that keeps an object moving in a circle is called **centripetal force.**
 * The acceleration associated with a car turning in circles is referred to as centripetal acceleration.

Force (F with an arrow on top.....F->). The Units for force are in Newtons (N)

1. Friction (Fr-->) Units are in Newtons (N) 2. Tension (Ft-->) Units are in Newtons (N) 3. Normal (Fn-->) Units are in Newtons (N) 4. Centripetal Force (Fc-->) Units are in Newtons (N)
 * There are two types of friction:
 * Static- Stays still
 * Kinetic- once the object is moving, the friction that the object has
 * Fc-->= ma --> Fc= mv^2/ radius

1. A 1 kg ball travels in a circular path at the end of a 1.5 meter string. It makes 25 revolutions in 10 seconds. What is the tension in the string?
 * Example:**

Fc= 1(23.55)^2/1.5 554.6/1.5= **369.7 N**

**__Chapter 2 Section 3-__**

 * What do you see?**
 * What do you think?**
 * What do you think?**