Two blocks A and B of mass mA and m9 respectively are kept in contact on a frictionless table. The experimenter pushes the block A from behind so that the blocks accelerate. If the block A exerts a force F on the block B, what is the force exerted by the experimenter on A?
Let 
be the force by the experimenter.
From the FBD of block A,
---(1)
From the FBD of block A,
---(2)
∴ equation (1) becomes, 
Equating acceleration from both the equations, we get
Thus, answer is, 
1