Acceleration of pulleys and blocks are as shown in the figure. All pulleys & strings are massless & frictionless magnitude of `a_(A)` and `a_(B)` are :
.

Options

A. `a_(A) = 0, a_(B) = 7`
B. `a_(A) = 0, a_(B) = 5`
C. `a_(A) = 0, a_(B) = 12`
D. `a_(A) = 5, a_(B) = 7`

Answer

C

Explanation

`1+(2+a_(A))/(2) rArr a_(A)=0` take upward
direction positive
a of pulley at right hand side
`3=(1+a)/(2) rArr a= 5m//_(2)`
`5=(-2 +a_(B))/(2) rArr a_(B) =12 m//s_(2)`