# A small puck of mass m and speed v0slides on a frictionless table and collides with a

## Question:

A small puck of mass m and speed v0 slides on a frictionless table and collides with a barbell (total mass 2M), as shown in the figure. The barbell, which is free to rotate about a fixed axle through its center, is initially at rest. The length of the barbell is d. The puck and the barbell stick together after contact. Consider the system consisting of both the puck and the barbell.

a) When analyzing collisions, we often approximate the total momentum of the system to be the same just before and just after the collision. Why is this not a good approximation in this case?

b) Does the total angular momentum of the system about the axle change during the collision?

c) Determine the final speed of the puck just after the collision.

d) Determine the angular speed of the system about the axle after the collision.

e) Determine the ratio of the final and initial kinetic energy of the system decreases. You should find that Kf/Ki

**Related Book For**

## Fundamentals of Ethics for Scientists and Engineers

ISBN: 978-0195134889

1st Edition

Authors: Edmund G. Seebauer, Robert L. Barry