Question

A ball rolls onto the path of your car as you drive down a quiet neighborhood street. To avoid hitting the child that runs to retrieve the ball, you apply your brakes for 1.05 s. The car slows down from 15.0 m/s to 9.00 m/s. The mass of the car is 1250 kg. (a) During the time the brakes were applied, what was the average force (in N) exerted on your car?

Answer 1

Answer:

F = 7.143 kN

Explanation:

given,

time taken to apply break = 1.05 s

car slows down from 15 m/s to 9 m/s

mass of the car = 1250 Kg

force is equal to the change in momentum with respect to time.

$F = \dfrac{\Delta P}{t}$

$F = \dfrac{m(v_f - v_i)}{t}$

$F = \dfrac{1250\times (9 - 15)}{1.05}$

$F = \dfrac{-7500}{1.05}$

F = -7142.85 N

F = - 7.143 kN

Force is acting opposite direction of velocity of car i.e. the sign is negative.