Question

Momentum & Impulse Question

See attached photo.

Answer 1

The first part has to do with change in kinetic energy. Kinetic energy is defined as \(KE = \frac{1}{2} m v^2\). You know the mass of the ball and it's initial velocity, so you can find its initial kinetic energy. When it strikes the wall, it loses 20% of it's kinetic energy. So, \(KE_f = 0.8 KE_i = 0.8 \left( \frac{1}{2} mv^2 \right) \). You can use this to find the final velocity.
Now, for the second part: once you have the final velocity, you can calculate the impulse with the change in momentum: \(J = \Delta p = mv_f-mv_i\). Remember that the initial velocity is positive and the final velocity is negative, and you can confirm the value for J.

Answer 2

Hi @BTaylor! I know it is too late now to say thank you, but I just want to say thanks! :D You really helped me understand the process of solving this problem.

Answer 3

No problem! Glad to help.