In the figure acceleration of `A` is `1m//s^(2)` upward, acceleration of `B` is `7m//s^(2)` upward acceleration of `C` is `2m//s^(2)` upward. The acceleration of `D` will be.

Options

A. `7 m//s^(2)` downwards
B. `2 m//s^(2)` downwards
C. `10 m//s^(2)` downwards
D. `8 m//s^(2)` downwards

Answer

C

Explanation

`a_(1)+a_(2)=1`
`a_(1)-a_(2)=7`
`a_(3)-a_(1)=2`
`rArr a_(1)=4`,
`a_(2)=-3`,
`a_(3)=6`
Acceleration of D`=a_(1)+a_(3)`
`=4+6=10 ms^(-2)` downwords