Question

Last question from me
Suppose the driver in this example is now moving with speed 39.6 m/s, and slams on the brakes, stopping the car in 4.1 s.
(a) Find the acceleration assuming the acceleration is constant.
m/s2

(b) Find the distance the car travels, assuming the acceleration is constant.
m

(c) Find the average velocity.
m/s

Answer 1

average speed during stop = (39.6+0)/2 = 19.8 m/s (a is constant so v is linear) That is part C answer.
time to stop = 4.1 s
so distance to stop = 4.1*19.8 = 81.2 meters (part B answer)
v = Vi + a t
0 = 39.6 + a(4.1)
a = -9.66 m/s^2 part A answer
a is negative of course because de accelerating

Answer 2

By the way, that is a little less than 1 g. He indeed slammed the brake on.

Answer 3

a. Vo + a*t = 0.
30.6 + a*4.1 = 0,
a = -7.5 m/s^2.

b. Vo^2 + 2a*d = V^2.
30.6^2 - 7.5d = 0,
d =

c. Vavg. = (Vo = +V)/2 = (30.6+0)/2 =

Answer 4

39.6 I think :)

Answer 5

Yes, 39.6. My mistake.

Answer 6

help

ppose the driver in this example is now moving with speed 38.9 m/s, and slams on the brakes, stopping the car in 4.4 s.
(a) Find the acceleration assuming the acceleration is constant.

Incorrect: Your answer is incorrect.

Your response differs from the correct answer by more than 10%. Double check your calculations. m/s2

(b) Find the distance the car travels, assuming the acceleration is constant.

Incorrect: Your answer is incorrect.

Your response differs from the correct answer by more than 10%. Double check your calculations. m

(c) Find the average velocity.

Incorrect: Your answer is incorrect.
m/s