Final velocity of an elastic collision between a ball and a plank on a frictionless s

  • #1

Homework Statement


Currently studying for a physics final on Wednesday 12/12/12
The problem can be found here


Homework Equations


Not very sure.

vfball=(v0(mball-mplank)+2mplankv0,plank)/(mball+mplank)
mballv0=(mball+mplank)vf

The Attempt at a Solution


I have no idea how to do a. I've tried
vfball=(v0(mball-mplank)+2mplankv0,plank)/(mball+mplank)
But it just comes to 0.

b.
I've thought about it and the only possible way to get the answer given that I can think of is this:
mballv0=(mball+mplank)vf
mv0=2mvf
vf=v0/2

Does this involve angular momentum as well? Or inertia? Any help would be gratefully appreciated!
 

Answers and Replies

  • #2
gneill
Mentor
20,874
2,837


Yes, angular momentum is involved, as is rotational KE. So, start by writing all the conservation equations.
 

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