A bead `B` of mass `'m'` can travel without frictionn on a smooth horizontalwire `"xx"^(')`. The bead is connected to a block of identical mass by an ideal string passing over an ideal pulley. The system, as shown, is in vertical plane.

System is initially released from rest in the position shown. Initial acceleration of block `A` is:

Options

A. zero
B. `g/2`
C. `(3g)/7`
D. `(4g)/7`

Answer

C, D

Explanation

`mg-T=ma_(1)`
`Tcos30^(@)=ma_(2)`
and `a_(2) cos 30^(@)=a_(1)`
`impliesmg=ma_(1)(1+ 1/(cos^(2)30^(@)))`
`implies a_(1)=(3g)/7`