# Angular SHM and friction

1. Jun 1, 2010

### bballman1441

1. The problem statement, all variables and given/known data

You set your pencil on the very edge of a swing and start rotating the swing to see how far you can wind it up before the pencil slips off while unwinding. The swing is simply a rope hanging from a tree and passing through the center of a flat plywood board. The rope has a torsional constant = 1 x 10^-2 Nm, and the board is 15 cm x 30 cm with a mass of 1 kg. Assume the pencil is at a point 15 c from the center, and has a coefficient of static friction= .3. Through what maximum angle (in radians) can you rotate the swing so that when you releasit it the pencil does not slip?

2. Relevant equations
w=sqrt(k/I)

3. The attempt at a solution
Figure out what force the pencil with coefficient of static friction can handle and figure out what angular acceleration creates that force.

I'm confused about other relevant equations and where to really start picking apart the problem.