Question

A compact car, mass 660 kg, is moving at 1.00 ✕ 102 km/h toward the east. The driver of the compact car suddenly applies the brakes hard for 2.1 s. As a result, an average force of 4.8 ✕ 103 N is exerted on the car to slow it down. (a) What is the change in momentum, that is the magnitude and direction of the impulse on the car?

Answer 1

Answer:

-10,080N/s

Explanation:

Change in momentum = Force × time

Given : F = 4.8 × 10^3N

Time,t = 2.1seconds

Change in momentum = (4.8×10^3)×2.1 =-

-1 0,080N/s

The negative sign shows that the force is opposite the direction of the velocity.

Answer 2

Answer:$59.43\times 10^3 kg-m/s$

Explanation:

Given

mass of car $m=660 kg$

Initial velocity of car $=102 km/h\approx 28.33 m/s$ towards east

Time taken to stop $t=2.1 s$

Force exerted $F_{avg}=4.8\times 10^3 N$

change in momentum is given  by impulse imparted to the car

$Impulse(J)=-F\cdot t$

$J=-4.8\times 10^3\times 2.1$

$J=-59.49\times 10^3 kg-m/s$

negative Sign indicates that impulse is imparted opposite to the direction of motion

magnitude of momentum $J=59.49\times 10^3$