Two identical uniform discs of mass `m` and radius `r` are arranged as shown in the figure. If `alpha` is the angular acceleration of the lower disc and `a_(cm)` is acceleration of centre of mass of the lower disc, then relation among `a_(cm), alpha` and `r` is

Answer

2

Explanation

`Tr=(mr^(2))/2 alpha.....(1)`
`Tr=(mr^(2))/2 alpha.....(2)`

From (1) and (2)
`"acc"^(n)`. Of point `b="acc"^(n)` of point a ltbRgt `ralpha_(1)=a_(cm)-ralpha`
Hence `2r alpha =a_(cm)`