The block of mass m is in equilibrium relative to the smooth wedge of mass M which is pushed by a horizontal force F. Find pseudo force acting on (a) m, (b)M as viewed by the observer sitting on the wedge. Will these pseudo forces (c ) equal and opposite, action reaction pairs? Explain.

Explanation

The acceleration of the system (wedge`+`block)
`a=(F)/((M+m))`(rightward)
the pseudo force on the block m will act in left direction
`(vecF_m)_(pseudo)=mveca=-m((F)/(M+m))(hati)`
The observer sitting on the wedge will also move with the acceleration of the system. Hence pseudo force on the wedge
`(vecF_M)_(pseudo)=Mveca=-M((F)/(M+m))(hati)`
The pseudo force is not a real force so it will not have any action-reaction pairs.