I'm trying to solve a problem from Richard P. Feynman's(adsbygoogle = window.adsbygoogle || []).push({}); Tips on Physicsthat I was assigned for homework. It's problem **I-5 in the book, if that helps at all.

Here is the problem:

A plank of weight W and length [tex]R\sqrt{3}[/tex] lies in a smooth circular trough of radius R. At one end of the trough is a weight W/2. Calculate the angle that the plank makes with the horizontal.

I tried to use equilibrium tactics, creating two normal forces and one gravity force at the plank-weight system's center of mass. I then used net force equations and net torque equations to solve for the angle. But this failed. Since it is a circle, the normal forces are not vertical or horizontal.

How am I supposed to do this?

P.S. Is it possible to use Latex to format stuff on these forums?

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# Homework Help: (Mechanics) A Plank in a Circular Trough

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