The cylinder shown is of weight W and radius r. Express in terms W and r the magnitude of the largest couple M that can be applied to the cylinder if it is not to rotate, assuming the coefficient of static friction to be
(a) zero at A and 0.30 at B,
(b) 0.25 at A and 0.30 at B.
![342_676350c6-affb-464d-bc89-d01819a4d13f.png](https://secure.tutorsglobe.com/CMSImages/342_676350c6-affb-464d-bc89-d01819a4d13f.png)