Two blocks of masses `8kg` and `6kg` are connected with a string `&` placed on a rough horizontal surface. Surface itself is accelerating up with constant acceleration `2m//s^(2)`. Two forces `60 N` each are acting on the two blocks as shown. Friction coefficient for `8kg` is `0.5 &` that for `6 kg` is `0.6.` Tension in the string is : `(g=10m//s^(2))`

Options

A. `60N`
B. `12N`
C. `42.2N`
D. `16.8N`

Answer

D

Explanation

`f_(R)` for `8kg=0.5xx8(10+2)=48N`
`f_(N)` for `6kg=0.6xx6(10+2)=43.2N`
It can be verified that limiting friction will act on `6kg`
From `FBO`, tension `=16.8N`