Two blocks of masses `4 kg` and `6 kg` are kept on a rough horizontal surface as shown. If the acceleration of `6 kg` block is `5n`, then `n` is :

Answer

2

Explanation

Check, whether they will move together or not.
For `4 kg` block
`a_(1) = (50 - 0.5 xx 4g)/(4) = 7.5 m//s^(2)`
For `6 kg` block
`a_(2) = (90 - 0.5 xx 6g)/(6) = 10 m//s^(2)`
`a_(2) gt a_(1) rArr` string gets slack
`10 m/s^(2)`.