# How do I properly set up this F.B.D.?

## Homework Statement

A uniform solid cylinder of wood rolls without slipping down an incline of angle theta. the coefficient of static friction is μs and kinetic friction is μk. Find the acceleration of the center of mass of the cylinder.

## Homework Equations

mgsin(theta)-μk = ma

## The Attempt at a Solution

My question is really how to reconcile with the static friction coefficient. Should this be included in my FBD and so my equation? Or would I just be using the μk and not the μs? If μs is to be included, can you please explain how? Would I have to set up two equations, one to overcome the static friction and the other to characterize the rolling motion with μk, then solve for the acceleration using a two-equation system?

## Answers and Replies

Doc Al
Mentor
You are told that the cylinder rolls without slipping, thus the only friction involved is static friction. (Hint: Write two equations: one for rotation, one for translation.)

Vitani11