- #1
KDawgAtsu
- 12
- 0
I don't need a solution to this problem, I just need some help understanding a part of it.
The figure below shows a small mass, m, moving at an initial speed, v0 , colliding with a stick with
length, L, and mass, M. Both the mass and the stick lie on top of a table. The collision happens at the
tip of the stick. After the collision the mass continues in the same direction, but now with the speed, v.
For a specific value of the ratio m/M, the stick will collide with the small mass a second time. What is
this value, and how far will the small mass have traveled between collisions? Assume that the
collision is elastic.
Initial Angular Momentum: (L/2)mv0
Angular Momentum After Collision: (1/12)mL2ω + (L/2)mv
I know that the rod and the particle must be moving at same linear velocities for the second collision to happen. What I don't 100% understand is why the angular momentum for the particle after the collision is still (L/2)mv. Initially, the origin is at the center of the rod, but after the collision both the particle and the rod move to the right. I don't understand why, for the particle, the distance for the angular momentum is just (L/2); doesn't this place the origin at the center of mass of the rod, which is now moving and thus a noninertial frame?
Thanks for the help!
Homework Statement
The figure below shows a small mass, m, moving at an initial speed, v0 , colliding with a stick with
length, L, and mass, M. Both the mass and the stick lie on top of a table. The collision happens at the
tip of the stick. After the collision the mass continues in the same direction, but now with the speed, v.
For a specific value of the ratio m/M, the stick will collide with the small mass a second time. What is
this value, and how far will the small mass have traveled between collisions? Assume that the
collision is elastic.
Homework Equations
Initial Angular Momentum: (L/2)mv0
Angular Momentum After Collision: (1/12)mL2ω + (L/2)mv
The Attempt at a Solution
I know that the rod and the particle must be moving at same linear velocities for the second collision to happen. What I don't 100% understand is why the angular momentum for the particle after the collision is still (L/2)mv. Initially, the origin is at the center of the rod, but after the collision both the particle and the rod move to the right. I don't understand why, for the particle, the distance for the angular momentum is just (L/2); doesn't this place the origin at the center of mass of the rod, which is now moving and thus a noninertial frame?
Thanks for the help!