Question

A 1600 kg car with the brakes applied comes to a stop in 4.20 seconds. During these 4.20 seconds the force of friction slowing down the car is 3900 N. What is the change in momentum of the car?

Answer 1

Answer:

The change in momentum of the car is 16380.8 kg.m/s

Explanation:

Given;

mass of the car, m = 1600 kg

time of motion, t = 4.20s

force of friction on the car, F = 3900 N

final velocity of the car after the brakes were applied, v = 0

The initial velocity of the car during the motion is calculated as;

$F = ma = \frac{mu}{t} \\\\mu = Ft\\\\u = \frac{Ft}{m} \\\\u = \frac{3900\times 4.2}{1600} \\\\u = 10.238 \ m/s$

The change in momentum of the car is calculated as;

ΔP = mu

ΔP = 1600 x 10.238

ΔP = 16380.8 kg.m/s