A block of mass `m` is attached at the end of an inextensible string which is wound over a rough pulley of mass `M` and radius `R` figure a. Assume the stirng does not slide over the pulley. Find the acceleration of the block when released.

Options

A. `(2mg)/(m+M)`
B. `(2mg)/(2m+M)`
C. `(mg)/(2m+M)`
D. `(mg)/(m+M)`

Answer

B

Explanation

`mg-T=ma, a=alphaR, TR=((MR^(2))/2)alpha`
`alpha=(2T)/(MR), :. A=(2mg)/(2m+M)`