# Homework Help: Spinning rod dropping on a pivot

1. Feb 4, 2009

### mjolnir80

1. The problem statement, all variables and given/known data
a long, thin rod of mass M and length L is standing stright up on a table. its lower end rotates on a frictionless pivot. a very slight push causes the rod to fall over. as it hits the table, what are (a) the angular velocity and (b) the speed of the tip of the rod?

2. Relevant equations

3. The attempt at a solution
could we set up a conservation of energy equation for this?
1/2I(for spinning of rod)$$\omega$$^2 + mgh = 1/2 I(for spinning of rod)$$\omega$$^2 + 1/2I(for dropping of rod)$$\omega$$^2

2. Feb 5, 2009

### LowlyPion

I'd suggest that there is only rotational kinetic energy to consider.

And it gets fed by the PE of the center of mass doesn't it?