In the figure shown all the surface are smooth. All the blocks A, B and C are movable, positive x-axis is horizontal and positive y-axis vertical as shown. Just after the system is released from the position as shown.
Acceleration of 'A' relative to ground is in negative y-direction
Acceleration of 'A' relative to B is in positive x-direction
The horizontal acceleration of 'B' relative to ground is in negative x-direction.
The acceleration of 'B' relative to ground directed along the inclined surface of 'C' is greater than g sin.
(a) A will move along the (-ve) y direction as there are no horizontal forces and the net downward force will be (mg - N)
The horizontal acceleration of B with respect to ground will be in the (-ve) x direction
Due to the component of Normal force from C
(c) As A can move only in the vertical direction with respect ground its horizontal acceleration should be zero. And since B has a horizontal acceleration be the (-ve) x direction, horizontal acceleration of A with respect B will be positive.
(d) The net force along the surface of B will be greater than mB g sinθ as there will be a component from the normal force exerted by A on B. ∴ the acceleration will be greater than g sin θ.