A speeding car is going 72 mi/hr. The driver hits the brakes to slow the car down to the 45 mi/hr speed limit. The car has a mass of 1.0 metric tons. What is the magnitude of the impulse on the car?

I = - 12070 N. s

Explanation:

Given that:

mass of 1.0 metric tons = 1000 kg

initial speed = 72mi/hr = 32.19 m/s

final speed = 45mi/hr = 20.12 m/s

Impulse = change in momentum

I = mv-mu

I = m (v-u)

I = 10³ (20.12 - 32.19)

I = 10³ (-12.07)

I = - 12070 N. s

The negative sign signifies that the impulse way is to the opposite direction.