Block B of mass m has been placed on block A of mass 3 m as shown. Block A rests on a smooth horizontal table. `F_(1)` is the maximum horizontal force that can be applied on the block A such that there is no slipping between the blocks. Similarly, `F_(2)` is the maximum horizontal force that can be applied on the block B so that the two blocks move together without slipping on each other. When `F_(1) "and" F_(2)` both are applied together as shown in figure.

(a) Find the friction force acting between the blocks.
(b) Acceleration of the two blocks.
(c) If `F_(2)` is decreased a little, what will be direction of friction acting on B.

Answer

(a) Zero
(b) `(F_(1))/(3m) = (F_(2))/(m)`
(c) To right