Section+5,+Chapter+1

SECTION 5

What do you think?


 * What factors must you consider to determine if you will be able in the distance between you and an animal to avoid hitting it?**

You must consider many factors include if the road is wet, and what condition is the road in (recently paved or not). Other factors include distractions, type of tire, condition of breaks, velocity, distance and reaction time.

INVESTIGATION PARTS 7 and 8
 * What is the goal of this part of the investigation?
 * One goal of this part of the investigation is to find out how tripling the initial speed of an object and how it affects the braking distance.
 * How does it relate back to the topic of the chapter?
 * We are trying to figure out about negative acceleration.
 * What equipment will you need? What will you measure?
 * In this experiment, you are measuring the braking distance

INVESTIGATION

1. A. B. We graphed it so that as the speed increases, which was on the x axis, the braking distance increased, which was on the y axis.

2. We will have the cart starting at different distances, such as far, medium and short. This will in turn control the velocity at which the cart goes at.

4) paper is 12.5 cm TRIAL 1 - REALLY FAST time in gate was .076690 INitial speed is 1.63 m/s distance traveled from sensor: 3.24 m

TRIAL 2- SORTA SLOW time in gate was: .207170 initial speed is: .60 m/s distance traveled from sensor: 3.05 m

TRIAL 3: REALLY SLOW time in gate was: .234588 Initial Speed is: .53 m/s distance traveled from sensor: 3.04 m

5 A.

b) As the initial speed gets greater, the braking distance will also increase. c) Our graph is virtually the same compared to the one we predicted in question 1. d) Most of our graphs are the same as those of other groups. e) It makes me feel more confident to have our graph look the same as others.

6) a) The braking distance will increase because you are doubling the initial speed. Therefore, your braking distance will double.

7) a) The effect of tripling the initial speed will having the braking distance triple. b) The effect of quadrupling the initial speed will having the braking distance quadruple.

8. A. The breaking distance information is found in the Breaking section.

B. I expect the breaking distance to be greater proportionally than the increase in speed. The ratio of the breaking distance is 209/11. The increase of braking distance is 177% compared to the speed increase of 133%, which is over double. There is a 44% difference between the increase in speed and increase in stopping distance. The reason the breaking distance was greater than the acceleration proportionally is because as a car goes faster, the kinetic energy keeps the car moving, meaning more energy is needed to counteract the increased kinetic energy.

C. In the beginning of question 8, it is suggested that breaking distance is directly proportionate to speed. We found this incorrect as there was more braking distance proportionately than then when the speed increased.

Physics Talk Checking up

Vf2= 2ad + vi2

Negative acceleration: slowing down or going in reverse.

Positive acceleration: gaining velocity in the positive direction

1. **If a vehicle is traveling at a constant velocity and comes to a sudden stop, has it undergone negative or positive acceleration? Explain your answer.** The vehicle has gone through negative acceleration. Positive acceleration would be if the vehicle had gained speed going forward. Negative acceleration would be accelerating in the opposite direction as the velocity is going, resulting in slowing down.

2. **Explain how you know increasing the velocity increases the breaking distance.** As velocity increases, the velocity and kinetic energy increases. This means that it would take more energy to bring the vehicle to rest.

3. **Why is the term negative acceleration used instead of deceleration?** Deceleration refers to a vehicle only slowing down. Negative acceleration refers to a vehicle slowing down in the current direction, and accelerating in the opposite direction.

Class Notes: -20%/5t

Physics to Go

1.

2. I think that Car B. is more dangerous because the slope is steeper, showing that as the velocity increases, the braking distance increases more than Car A. Car A. has a lower slope, going farther to the right than it did going up, showing that it can go faster while braking in less distance than Car B. In general, Car B. is higher on the y-axis than Car A is, showing greater braking distance.

4. It would be 39 meters because if it is .9s for reaction time at 10m/s, then it would be 9 m before the driver reacted, and if it takes 30 m to react, then the answer would be 39 m to stop. Vx + bd= tsd x = reaction time V = velocity bd= braking distance TSD = Total Stopping Distance.

Class Notes 10/24/11

breaking distance (fish thing) (Vi)2 Braking distance is proportioned to starting velocity squared

Homework 10/24/11

Motion Equations

(d=v(with bar)t) = distance equals average velocity times time. Tells average speed. (vf=at + vi) = final velocity equals acceleration times time plus initial velocity. Acceleration. (v(with bar)= vf+vi/2) = average velocity equals final velocity plus initial velocity over 2. Average velocity with consistent acceleration. (D=1/2at2 + VIt) = Distance equals one half acceleration time squared plus initial velocity time. Distance with acceleration and time, without final velocity. (Vf2= 2ad + vi2) = Final velocity squared equals 2 acceleration times distance plus initial velocity squared. Stopping distance to the acceleration and velocity without the need to calculate the time.

Graphing: 1/2 b h= 1/2 VF x T = (average veleocity) x (time)

Active Physics Plus

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