Question

a car with a mass of 1,400 kg is moving at a speed of 30 m/s. the driver applies the brakes, and the car comes to a stop in 8 seconds. what is the impulse applied to the car?
a. -42,000 n·s
b. -24,000 n·s
c. -6,000 n·s
d. -10,000 n·s

Explanation:

Step1: Recall the impulse - momentum theorem

Impulse \(J=\Delta p = m(v_f - v_i)\)
Given \(m = 1400\space kg\), \(v_i=30\space m/s\), \(v_f = 0\space m/s\)

Step2: Substitute the values into the formula

\(J=1400\times(0 - 30)\)
\(J=1400\times(- 30)\)
\(J=-42000\space N\cdot s\)

Answer:

A. \(-42,000\space N\cdot s\)