1. A 700kg racecar slowed from 30m/s to 15 m/s. What was its change in Momentum? 2. If the car in the above problem took 5 seconds to slow down from 30m/s to 15 m/s. a. What is the impulse? b. What was the average force applied by the brakes?

Question

Kaeden Pitts

Physics

7 September, 21:58

1. A 700kg racecar slowed from 30m/s to 15 m/s. What was its change in Momentum? 2. If the car in the above problem took 5 seconds to slow down from 30m/s to 15 m/s. a. What is the impulse? b. What was the average force applied by the brakes?

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Answers (1)

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Mollie Macdonald · Answer 1

1. The change in momentum follows the formula:

Change in Momentum = mΔv,

where m is the mass and v is the velocity

Change in momentum = (700 kg) (15 m/s - 30 m/s) = - 10,500 kg·m/s

2. For this problem, the formula for impulse, J, is

J = FΔt

Before answering part a, we answer for part b first.

Part B.

F = ma

where

a = Δv/t = (15 - 30) / 5 = - 1 m/s²

So,

F = (700 kg) (-1 m/s²) = - 700 N

Part A.

J = (-700 N) (5 s) = - 3,500 N·s