Chapter+1

Driving the Roads toc =Section 1:=
 * Chapter 1**

What do you see?
I see a yellow car colliding with an orange car that is flipped over, with oil coming out, and i see the blue car rushing to a halt to try and not hit the other two cars. the curved road, mountain roads, it seems like they are on a hill. What do you think?


 * what factors affect the time you need to react to an emergency situation while driving?**

distractions like the radio, people in your car, you looking at something else(scenery), cell phones, if you are not focused on the road and what cars are doing in front of you, you will not have enough time to react to something happening suddenly

**Investigate:**

 * First investigation**: being by finding how long it takes to move your right foot between imaginary gas and brake pedals

My reaction time: 0.42 seconds 0.42 seconds 0.45 seconds average reaction time: 0.43 seconds

My partners reaction time: 0.38 seconds 0.38 seconds 0.42 seconds average reaction time: 0.39

My reaction time: 0.65 seconds 0.73 seconds 1.00 seconds average reaction time: 0.80 seconds
 * second investigation:** test your reaction time by having a classmate stand behind you and clap, when you hear the sound, move your foot between the imaginary pedals.

my partners reaction time: 0.35 seconds 0.58 seconds 0.50 seconds average reaction time: 0.48 seconds


 * Third investigation**: one student starts both stopwatches at the same time and gives one to their partner. first student stops theirs and their partner stops theirs too. the difference is the reaction time

my partner's reaction times: 0.21 seconds 0.19 seconds 0.08 seconds average reaction time: 0.16 seconds

my reaction time: 0.35 seconds 0.34 seconds 0.34 seconds average reaction time: 0.33 seconds


 * Fourth investigation**: partner dropping a ruler and other partner catching a ruler and measuring reaction time according to how many cm you caught it on.

my reaction time: 28 cm/ 0.24 seconds 15 cm/ 0.17 seconds 15 cm/ 0.17 second average reaction time: 0.19 seconds

my partners reaction time 19 cm/ 19cm 20cm average reaction time 0.2 seconds




 * Fifth investigation:**

a.) when i did not to think about whether to catch it or not, my reaction time was faster because i already knew what i was doing. But, with the green and red experiment, i did not know if i was to catch it or not, so it took me longer to react because i did not know what i was doing.


 * Sixth investigation:**

50cm 15cm 18cm 49cm

a. my reaction time seemed to double, since i had distractions, so it took me longer to react. When i knew what i was doing and i could watch the person speak, i had a better reaction time, but when i was not looking, it took me longer to react.

b. ten things that could distract me from driving safely are: talking on the phone, texting on your phone, radio, friends, weather, traffic, gps, drinking/drugs, eating, changing clothes.

Physics talk
Checking up: //If you were driving, and you were distracted by something, you would react slower to something on the road because your attention was on the distraction, so you would not react as fast as if you had your eyes on the road.// //This is illegal because both alcohol and drugs slow your reaction time. They both distract you just by taking them. This gives you a greater chance of getting into an accident. Most kids in car accidents are drunk or on drugs, and it is because they didn't react fast enough.// //Eating, putting on makeup, music//
 * 1. how do distractions affect reaction time?**
 * 2.Why is driving under the influence of alcohol or drugs illegal?**
 * 3. Name three factors in addition to distractions and drugs or alcohol that could affect reaction time**

Physics Plus:
1. when calculating, d=1/2 at^2 so the equation is d=distance, a=980 cm squared, and t= time of fall in seconds

2. i measured the distance of fall for the ruler and the calculated the reaction time. 3. then i made a reaction time ruler with the distance measurement converted to time. 4.



What do you think now?
The factors that affect the time you need to react to an emergency situation while driving are the radio, eating, any distraction that can take your eyes off the road for just one second.
 * 1. What factors affect the time you need to react to an emergency situation while driving?**

Essential Questions:
1**.What is reaction time?** reaction time is the time it takes you to react to something that has just happened.

2.**How did you measure reaction time in this section? What was the range of reaction times obtained by other students in your class**? We measured the reaction time in seconds because it is more precise. The range of reaction times was varied because of the different examples of reaction time situations we did.

3. **Describe how reaction time is a measure of change over time** reaction time is a measure of change over time because the reaction time is you changing what you are doing and reacting to what you see and then the time is how long it takes you to react.

4. **why should you care?** It is important to care because if you have a good reaction time, you will respond quicker to driving situations. Sometimes, you need to be abrupt in stopping, or turning, and you have to be aware of what is going on around you, and be able to react fast to something that could happen without you knowing.

Physics to Go//://
1//. Mom: 29.5 cm 24.5 cm 11 cm// //Dad: 18cm, 21cm, 17.5cm// //Tatiana(sister): 24 cm, 21cm, 22cm// 2. It seemed that the reaction times i obtained in class showed that me and my partner had faster reaction times since we had a better understanding of what we were doing. We were already preparing ourselves to react fast,so we had a faster reaction time. 4. At first you would think that the race car driver would need faster reaction time however, as a new driver i have realized that you need very fast reaction times to drive through a school zone. Not only could there be small children, there could be animals, game balls, kids running across the street, and if you take your eyes off the road for one second, you don't know what could happen. As a race car driver, they only need to pay attention to the road, and the other drivers. There are more dangers in a school zone than a race track so drivers need a faster reaction time in a school zone. 5. Alcohol, changing radio stations, or talking on a cell phone can slow down your reaction time, which could cause an accident. 6. If ones reaction time is slower rather than quick, the consequences could be fatal. 7. Teenagers seem to be more easily distracted and they do not have as much experience and can not handle the distractions as well as a more experienced driver. 8. I learned that in order to be a safe driver, i must have a fast reaction time because if you do not react fast enough you could cause not only yourself, but other drivers to be in danger. Teenagers need to limit their distractions. When i drive, i never use my cell phone and i try to only turn the radio station when i am at red lights becuase it takes my eyes off the road, which could lead into an accident if i am not careful.

= = =Section 2=

What do you see?

 * person recording data with a tape measure
 * two people comparing their strides
 * observer in a doorway
 * book next to the person recording data
 * man going in a ascending order/direction
 * obstacles/clutter

What do you think?

 * yes if they were measuring the same side or angle, but if they were measuring different sides of an object, they could be right, or maybe they had different measuring tools, or they started at different places, or possibly different units.
 * one of them didn't make a mistake, but one of them was more precise. They may have had a more precise instrument.

first investigation:
2a. record number of strides me: 37.5 strides my partner: 25 strides 3a. record length of stride me: 23 inches/59 cm my partner: 30 inches/76 cm 4a. calculating our number of strides by the length of strides we got 19 meters

with the other distance; my number of strides: 21 my partners number of strides: 14 multiply number of strides by length of strides,

my distance: 12.39 my partners distance: 10.64

5a. our measurements did not agree, but they were not too far away from each other. b. there are differences between different groups because of height, leg length, what clothing you are wearing 5c. measure each stride and then it is more accurate 6a. i was not in class for this 7.a.the measurements do not all agree but it is mostly varied in the 1,300 range, and there was one in the 1700 range. 7b. I think there wre differences with the measurements by difrent groups because you can not get an exact measurement with only a meter stick, and everyone is different heights as well. 7c. If we all used the same measurement tool, like a tape measure, and we observed each other doing the measurement, it would be more exact. 7d. I think that if we all used a very long tape measure, it would be much more exact because it is very precise. The values would probably be in the 1,300 section. I think that each group would get a very very close measurement to the other groups. It would be off by maybe one or two marks. 7e. i think there will always be some differences in the measurements because one person might think one number is going closer to another, or they might be more precise than the other. 3.1 and 3 are different, even though they are basically the same. 8a. the only systematic error we had was the ruler shifting, or the imperfection of the ruler, or us arguing that it was a certain measurement, when the other partner thought it was something else. 8b. our errors did not dramatically affect our measurements, they were very close or a few points off, but never very seriously off. 9a. this measurement is very reasonable. a weight can be defined by a scale, although it is not exact, it is very cloes to the true weight or mass of something. College football players are usually heavy according to all the muscle they have. 9b. This measurement is not very reasonable. Yes, basketball players are tall, but at the same time, there are not a lot of people that are 13 feet tall. i do not even know if this is possible. This is not a good estimate. 9c. Minutes are hard to measure. A teacher can not work that many minutes because that, according to hours is 24 hours per day, and a teacher can not possibly work that long in one day. 9d. this is unreasonable. A poodle is heavy, but most dogs are under 100 pounds, and very few dogs could weigh more than 110 lbs if even possible. 9e. This is an unreasonable estimate. A house is usually 3000 square feet, and classrooms are much smaller. classrooms are usually in the hundreds when it comes to square feet. 9f. This is a reasonable assumption for the distance across a high school, with all the sports fields and parking lots and other buildings. 9h. you must estimate how fast the truck is going, how fast you are going, and the time that it will take the truck to reach the spot you are in. It would be safer to estimate and wait for the truck to pass than to try and squeeze by and possibly get into an accident. 9i. This is reasonable, a motor home is usually the height of two or more of one small car, which is around 15 feet, and bycicles are not very tall, maybe 2 feet. So the motor home will make it through.

Checking up:
1. Systematic errors are errors that happen every time you do an experiment, or at each part of an experiment. A random error is something that happens once, out of the ordinary, and it skews your experiment just once. 2. There will always be uncertainty in measurement, because you could always be more precise, or someone might not be precise enough. also, from where people are standing, it could affect their sight of the measurement. 3. The arrows would have to be pointing up or down, instead of to a certain side, east or west.

**What do you think now?**

 * For both questions, it seems to be the same answer; either they had different tools, or one of them was more precise with their measurements. Also, one tool could be wrong, and could be changing their measurements each time, like a systematic error. You can reduce random errors by checking all of your tools, making sure they are the same length, and going over what you get from the experiment.

Essential Questions

 * What does it mean? These errors are systematic, because every time you measure something, you will be making an error. These errors affect precision and accuracy.
 * How do you know? The jeweler might not know what an ounce is because his measurement might be off, by just a little, but just enough to make a difference.
 * Why should you care? If you do not measure distances accurately, you could possibly get into an accident, because you did not have a correct calculation of distance from your vehicle and another vehicle driving.


 * physics plus**

distance over time: 2m/s=.02m/time

Physics to go:
4. the possible uncertainty is one barrel of oil could be just a ounce more than another, or it could be an ounce less, which would be cheating the person buying the oil for the oil tanker. 5. they say they are a certain amount of ounces, but the object holding the said amount could be too big, or too small, which would cause the amount to be less or more. 6a. it depends on how much people are drinking, but i would say if you filled up the cups halfway each, you could have enough. 6b. i think that it depends on how fast they are going, because if you are going faster, you will use up your gas quicker. 7. no yes, because say you could not take the bus because you were too close, but really they miscalculated by a meter, and you were able to take the bus, that is a big error. Also for the classroom, if you could not have as many kids as you were going to have, or not enough equipment because they thought there was not enough room, that is a big error. 8a. 60 mi/h 8b. they could time how long it takes you to drive a mile, and then see how far it was, to find out the speed. 9. I do not think you should get a ticket for that because the cop does not know how long you were going 21. What if you were only going that to speed up for a second, or something. maybe you were avoiding a garbage can and you had to speed up, or a garbage truck. and how do you know that his speed gun was correct? it takes a few seconds to get the real speed, and the cop could have been reading it too fast.

=Section 3=

what do you see?

 * car crash
 * people going fast
 * three cars bumping into each other
 * the cars look very compact
 * there is a bunny on the side of the road
 * on the other side, there is a body of water and a boat
 * there are different sizes and colors of cars
 * some of the people do not look too upset
 * only the person in the front of the crash looks upset
 * there is smoke coming out of the cars, which indicates that the cars are going fast
 * she was distracted by the bunny
 * the bunny and the mile marker match up

What do you think?

 * i think a safe distance between my car and the car in front of me is one car or 2 car lengths to be safe. this is because if they make an abrupt stop, you have time to stop yourself too so you do not hit it.
 * when i am driving, i determine how fast the car is going, how fast i am going, and what the road we are traveling on and then i determine a safe following distance. usually one or two cars length

Investigate
1&2a 2c

2b. No it is not the same distance, because as you go faster, in the same amount of time, you go farther with a faster speed. They were farther apart at 45 mph.

3a.

3b.



3c.



3d.



3e.If you are walking slower, you are covering less distance, but if you are walking faster, you cover more distance. if you look at the graph, it shows that when you are walking slower, the peak is smaller than if you were walking faster.

5a.



5b. I was pretty accurate when it came to what my graph would look like. it would be a gradual increase towards the sensor, and then a steep fall away from the sensor at a fast speed.

6a.



6b.

if you did not label, you would be able to tell because the one that is not as linear is the one that is slower, because it covers less space in the same amount of time, opposite to the one that was going fast, that covered a lot of space in the same amount of time.

7) a. In the latest trial I walked about 2.9 m in total. b. It took me about 2.9 s to walk 1.5 m. it took me 5.5 s to walk 1.4 m. c. My velocity for the green line was 0.517 m / s. My velocity for the red line was 0.254 m / s. d. I would multiply my velocity by the time I'd be walking for. The assumption is that the walker is walking at a constant rate.

8) a. The car travels about 30 ft. b. The car will go 90 ft. c. The car would go 25 ft. The car would move 75 ft. d. The car would go 35 ft. The car would go 105 ft. e. A driver should be at least 30 ft behind the other driver. f. It travels about 4 car lengths per second.

**Physics to Go:**
1a. the car is moving at a constant speed and going steadily 1b. The car at first is going at a constant speed, and then goes faster, and then goes slower than its constant speed. 2a. 2b. 3. the race car driver has traveled 17.2 feet in 20 seconds. 4a. her average speed was 47 miles per hour 4b. She was probably going somewhere close to 47 miles per hour. the average means that it is thin the middle of most of the speeds, so if she was going slower or faster than the average, it was not very far away from the average speed. 5.20 miles per hour 6a. the motion of the automobile is accelerating at a constant speed for a certain amount of time, and then evens out and is traveling at the same speed for a certain amount of time. 6b. the automobile first accelerates at a constant speed for a certain amount of time, then goes at the same speed for a certain amount of time, then the speed starts to decelerate at a constant speed for a certain amount of time. 6c. the automobile first is slowly accelerating and then around the half of the total time, it starts to accelerate a lot and really picks up speed fast for a short amount of time. 6d. the car is accelerating gradually and a constant speed for the amount of time it traveled. 7a. 7 meters per second 7b. 7c. 8a. i think that this is considered a safe following distance because it should not take a good driver more than 3 full seconds to react to what could be happening to the car in front of them, and it gives them time to react to the situation at hand. 8b. I think that when it comes to the highway, you should give yourself a little more distance, because there are more lanes, and cars are all around you, and could be changing lanes at any moment. this could cause an accident if you do not put enough space between you and the car in front of you. Also, if you are going faster, there is more room for you to stop when you are driving on the highway. 9a. you would travel 33 feet in that third of a second. 9b. yes it is, in most classrooms. 10a. 120 feet in .5 seconds (60/.5) 10b. 120/15 is 8 car lenghts 10c. your car would travel 60 feet in .5 seconds and that is 4 car lengths 10d.your car would travel 180 feet in .5 seconds at 90 miles per hour, and that is 10 car lengths. it is 1/2 of a football field 10e. they double the length you travel 11.



12.

**Essential Questions**
The speed 40 miles per hour means that in one hour you travel 40 miles. You can measure the speed of a vehicle by using your speedometer, or by using a mile marker and seeing how long it takes you to get there, then use d/t to find your velocity. The reaction distance depends on your reaction time because if you do not react in time, you will travel longer without reacting than if you had a fast reaction. if you sneeze, you have to react quick and make sure you open your eyes as soon as possible, but if you take a few seconds to react, you could get into an accident.
 * **What does it mean?**
 * **How do you know?**
 * **Why should you care?**

Physics Plus:
1. 2. 3a. i think the average speed is around 20 3b. average speed is

=Section 4:=


 * What do you see?**
 * red car is going really fast, accelerating very quickly
 * car is going to gradually accelerate. waiting for the person to cross the road
 * person dodging the car running onto the sidewalk with a dog
 * very open area
 * person waiting to cross on the other side of the road


 * What do you think?**

= = = =

Investigate:
1a. distance and time will increase together, so the speed will increase at the end, and it will take less time. 1c. this is our prediction



2a.

this is the actual graph



2b. my prediction and the actual graph were very similar which means that i had a good idea of what the graph's shape would be. 2c. 3) The car is going the slowest at 30 mph. The car is going the fastest at 60 mph. The car is covering more distance per second at 60 mph than 30 mph. All of these graphs depict my movement towards and away from the motion sensor. The first graph over lays my movement towards and away from the sensor at a slow pace. The second graph shows the my movement slowly The graph will curve up slowly, and drop down in an almost straight line. My prediction was just the opposite of how the graph turned out.

A person could tell which line was which because the one line covered more distance in less time while the other one covered less distance in a longer period of time. The line which covered more distance in less time was moving faster than the other line.

slope -rise over run/ delta d/ delta t delta t (run) delta d ( rise)

velocity = distance / time time = distance / velocity distance = velocity * time

5a. 5b. Our prediction was that it would form the shape of a, and we were correct. it will pick up pace, and then slow down dramatically. this is what the graph shows. As predicted the graph is a negative curve. 5c. 5d.the slope of the d-t graph changes and the speed decelerates as time goes by. 5e. change in velocity/ change in time 6a.It will have a curve going up away from the detector, in a parabolic shape



6b. the slope will gradually change



7a.

d-t graph



v-t graph



7b. my predictions were pretty similar to my outcomes with my graph. 7c. it gradually accelerates as times goes by, so it covers more distance in less time. 7d. the car accelerates very quickly, and the speed is very fast for such a short period of time, and then it evens out at rest. 7e.

8. a. cart is accelerating at a gradual speed and the speed is getting faster as time goes by it is covering more distance in less time. it is going away from the motion sensor b.cart is slowly accelerating, and then slowly comes to a rest away from the motion sensor at the bottom. c. cart is accelerating constantly towards the motion sensor d. cart is decelerating toward the motion sensor

9a. 40 miles per hour

11a.

vf -vo / time

11b. the velocity is changing the most during the period between 0 and 2 seconds. 11c.the velocity is changing the least between 6.6 and 8.7 seconds 11d. the acceleration is the greatest between 0 and 2 seconds. the acceleration is the least between 4.2 and 5.2 seconds as the time went on, the acceleration decreased gradually.

12a. yes. 12b. 12.c. the table indicates the greatest acceleration is also between 0 and 2 seconds.The graph has the steepest slope also between 0 and 2 seconds.

Physics Talk
this section is discussing acceleration. It talks about Gallileo and how we came up with the term acceleration. he used a water clock to figure it out.

Acceleration: A= change in velocity / change in time (average) A= delta v / delta t A= vf-vi / tf-ti

Accuracy and Precision- equipment

Vectors magnitude and direction ex. speed vs velocity speed - magnitude only (scalar) velocity- magnitude and direction ex. 25 mile/hr south

vector has a negative and positive value

speed up slow down change direction

Physics to Go:
1. Yes because an object can have a consistent velocity. 2. yes, for the one second when they stop, and they are at complete rest for just an instant. 3. Even though they are accelerating at the same speed, the initial velocity is unknown, so they may be getting faster at the same acelleration even though they might have a different velocity that they started with. 4. Yes, because if they had the same change in velocity, so the acceleration was equal. 5. yes because if you were accelerating from rest, and a car was keeping the same velocity from behind you, they would pass you 6. Yes, because speed signs also go with time and distance, and speed equals distance over time. this would show you how fast it would take you to travel a mile. It is also easier to figure out for time, speed, or distance. there is also negative velocity, so people would not be able to focus on driving and figure out the velocity. we use miles per hour. 7a.



7b. deltax- 1/2(vi+vf)(t)

=Section 5= = =

what do you see?

 * i see the car breaking very suddenly to stop before it hits the moose
 * the moose is in the middle of the road
 * the area seems to be close to a forest
 * the car looks like it is breaking so hard that the car it is being pulled back.

**What do you think?**

 * you have to consider how fast you are going, how fast you are going, how far away you are from the animal. if the animal is crossing, walking, running, the conditions of the road, uphill, downhill, what kind of car you are driving, your environment

Investigate:
1a. b. my hypothesis was that if the car has a smaller initial velocity, it will not go as far as a car with a larger initial velocity, and it will take less time to slow down because it is closer to zero than the car with the larger initial velocity. 4a. plot points .8 m/s/1.27m 1.22m/s/1.87m 1.4m/s/1.97m 1.72m/s/2.10m 1.88m/s/2m 1.8m/s2.29m 5a.

== 5b. if the initial speed is higher, the breaking distance is longer. 5c. it seemed accurate except for one point. 6a. the initial speed and the breaking speed should have doubled, but the data was not exact. 7a. we do not have two data points that one is three times the speed of the other. if it doubled for the doubled data, it should triple for the tripled data. 7b. this will times the distance by four. 8a. in the braking section 8b. i think the ratio of the braking distance will be the same, but it was not. it was equal to 1.77 8c. when looking at my data, i noticed that if the initial speed was high, the braking distance was high. if you double the speed, the distance should also double.

**What do you think now?**

 * i think the most important factor would be your speed and your environment around you, also your reaction time and knowing your reaction. it is not just one factor, but it is many factors that tie together to find out the most important factor.

**What does it mean?**

 * **it means that if you are going faster, it will take you a longer time to break. this is important so you can see how long it takes your car to stop for a stop sign, or a red light in a certain distance.**

**How do you know?**

 * **i know this because of our experiment of testing a car and its speed and it's braking distance. as the speed increased, the braking distance increased.**

**Why should you care?**

 * **this can help you be a safer driver because as you know you need to stop at a certain spot, you can ease your way down to a slow speed instead of suddenly hitting the brakes which is dangerous for your car and the cars around you. you need to be able to know how long it takes your car to stop at a certain speed.**

= = =Section 6=

**What do you see?**

 * **i see a red car halting very fast almost as if the car will flip over**
 * i see a lady waiting to cross the street. it seems like she was almost hit by the red car
 * i see the green car going through the red light
 * i see a lot of things coming out of the green car because they went very fast
 * the policeman is doing nothing
 * there is a dog flying out of the red car because it is going so fast

**What do you think?**

 * if all the traffic lights stayed yellow the same amount of time, people would be able to know if they could make the yellow light before it turns red, and it would not be so chaotic at the intersection.
 * an intersection with a traffic light is hectic and sometimes you get a green arrow and sometimes you don't. you can not expect it to be the same all the time.

Investigate
3a. Yes, because they are in the front, and they will accelerate so they can make it through, because they have at least 3 seconds. 3b. They are in the GO zone because they are in the front of the line, and they have enough time to make it through the box without it turning red, the two cars, however might not make it. 3c. If there was any automobile closer to the intersection than automobile A, it would be i the GO zone, because it would have enough time, if they accelerated fastly, and they would make it before the red light. 3d. Automobile C is not in the GO zone. If automobile C tries to make the yellow light, it will get stuck in the dilemma zone and get stuck in the box, which could cause an accident.

4a. Car E is in the stop zone because if the car tries to make it through the yelllow light, it willl not make it and it will be stuck in the middle of the intersection. 4b. F is in the Go zone because it has to go completely through the intersection. 4c. 5b.
 * zone || a || b || c || d || e || f ||
 * stop ||  ||   || x ||   || x ||   ||
 * go || x || x ||  || x ||   || x ||

6a.the Go zone is smaller than the stop zone. 6b. the go zone is bigger than the stop zone 6c. If you increase the yellow light time, you have more time to get through the, and if you were farther away from the go zone, you might be able to make it through with more time. 6d. if the yellow light is longer, more cars can pass through the intersection.

= = = = =Physics to Go= == 1a. The GO ZONE is 45 meters 1b. the STOP ZONE is 16.5 meters 1c.

2a.



2b. 3. If a person is listening to loud music it will increase their reaction time because they will be focusing on the music and they will not have full attention on the road, so if something happens, it will take them longer to stop. If they are pulling up to a red light, it will take them longer to stop. If the light is green, it will not affect the GO ZONE because they are not required to stop, and they can keep moving. This affects the stop zone because it has to be big enough so that the car does not hit another car.

4. If a car has worn tires and bad brakes it will take it longer to stop the car. This affects the STOP ZONE because it will take up more space for this car to stop. It affects the GO ZONE because if it was going through the go zone, it will be slower than other cars, so the GO ZONE will also have to be longer.

5. This delay is so cars that are not paying attention can see what is going on and catch up. Also, this could be because of a green left arrow on the other side, which gives the people turning left a chance to turn.

6. This problem is not good because it is too much time for the light. the light should be turning red at the end of the countdown instead of yellow. it affects the GO ZONE longer, and the STOP ZONE shorter.

7a. the GO ZONE is 48 meters, and the

8. I think that if we painted the lines of the GO and STOP zones this would help people figure out which zone they are going to make when they are coming up to an intersection. This would give people a better idea of where they stand. This could lead to more organized intersections.

=Essential Questions=

**What does it mean?**
the factors that determine the size of the GO ZONE, the STOP ZONE, and DILEMMA ZONE are velocity, acceleration, reaction time, width of intersection, and yellow light time.

=Investigate= 3.



4a. The washer is 13.5 cm from the center of the turntable 6a. 16.8 seconds 6b. 37.7 RPM 6c.1.68 6d. if you do the experiment more than once, you get a more average 6e. .59 revolutions per second. 7a.the speed is 71.7 centimeters per second 7b. 314.2 cm/sec 8a. i predict that the sandpaper will help the washer stay on the table because it gives it more grip 8b. 1.68 sec 8c. 71.1 cm/sec 8d. 180.87 9a. the bigger the radius, the greater the safe speed and distance 9b.

Physics talk: Physics talk discusses newton's laws of motion that explain why if you put a force on a car, it will turn around the corner instead of going straight. it summarizes centripetal force and centripetal acceleration. Centripetal force is the force between the thing in motion and the surface. Centripetal acceleration is the acceleration associated with an automobile changing direction.

forces that might act on an object traveling in a circular path: normal force centripetal force frictional force