A block the of mass `4kg` is placed on another block of mass `5kg` and the block `B` rests on a smooth horizontal table for sliding the block `A` on `B` a horizontal force `12N` is required to be applied force on it How much maximum horizontal force can be applied on 'B' s that both `A` and `B` move together? Also find out the accleration proudced by this force
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Explanation

Here `M_(1) =4kg` and `M_(2) = 5kg`
Limiting friction between the blocks is `f_(lim)` Acceleration of system is
`a = (F)/(M_(1)+M_(2)) = (F)/(4+5) =(F)/(9)m//s^(2)`
Because of this acceleration the block `A` experiences a peseudo force of magnitude
`F_(pseudo) =M_(1) a =4 xx (F)/(9)`
As block A move together with `B,F_(pseudo)le f_(lim)` For maximum value of applied force
`F_(pseudo) =f_(lim), (4F)/(9) =12 rArr F =27N`
The acceleration of blocks `= (27)/(9) =3m//s^(2)`
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