Question

In the figure shown all the surface are smooth. All the blocks A, B and C are movable, x-axis is horizontal and y-axis vertical as shown. Just after the system is released from the position as shown. 

(A) Acceleration of 'A' relative to ground is in negative y-direction 

(B) Acceleration of 'A' relative to B is in positive x-direction 

(C) The horizontal acceleration of 'B' relative to ground is in negative x-direction. 

(D) The acceleration of 'B' relative to ground along the inclined surface of 'C' is greater than g sin θ.

Answer 1

Correct option: (A, B, C, D)

Explanation:

(Tough) There is no horizontal force on block A, therefore it does not move in x-direction, whereas there is net downward force (mg – N) is acting on it, making its acceleration along negative y-direction. Block B moves downward as well as in negative x-direction. Downward acceleration of A and B will be equal due to constrain, thus w.r.t. B, A moves in positive x-direction

Due to the component of normal exterted by C on B, it moves in negative x-direction.

The force acting vertically downward on block B are mg and N_A (normal reaction due to block A). Hence the component of net force on block B along the inclined surface of B is greater than mg sinθ . Therefore the acceleration of 'B' relative to ground directed along the inclined surface of 'C' is greater than g sin θ