Preparing for Physics Final: Solving Homework Equations

AI Thread Summary
The discussion focuses on preparing for a physics final, specifically solving homework equations related to momentum and conservation principles. The user expresses confusion over the equations for a ball and plank system, particularly in calculating final velocities. They attempt to apply the equations but find their results lead to zero, raising questions about the involvement of angular momentum and inertia. Respondents confirm that angular momentum and rotational kinetic energy are relevant, advising the user to write out all conservation equations for clarity. Understanding these concepts is crucial for solving the problem effectively.
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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!
 
Physics news on Phys.org


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

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