A 4.0-kg particle is moving horizontally with a speed of 5.0 m/s when it strikes a vertical wall. The particle rebounds with a speed of 3.0 m/s. What is the magnitude of the impulse delivered to the particle?
A) 24 N⋅s
B) 32 N⋅s
C) 40 N⋅s
D) 30 N⋅s
E) 8.0 N⋅s

Question

Quizplus · Accepted Answer

Impulse is given by the change in momentum, which is mass times the change in velocity. The initial velocity is 5.0 m/s (towards the wall), and the final velocity is -3.0 m/s (away from the wall, assuming the opposite direction is negative). The change in velocity is -3.0 m/s - 5.0 m/s = -8.0 m/s. The mass is 4.0 kg, so the change in momentum (impulse) is 4.0 kg * -8.0 m/s = -32 kg⋅m/s. The magnitude of this impulse is 32 N⋅s.

A 40-Kg Particle Is Moving Horizontally with a Speed of 5