Two smooth block are placed at a smooth corner as shown in fig. Both the bloks are having mass m. We apply a force F on the block m. Block A presses block B in the normal direction, due to which pressing force on vertical wall will increase, and pressing force on the horizontal wall decreases, as we increases `F(theta = 37^(@)` with horizontal).

As soon as the pressing force on the horizontal wall by block B become zero, it will lose contact with ground. If the value of F further increases, block B will accelerate in the upward direction and simulaneously block A will towards right.
If both the blocks are stationary, the force exerted by ground of block A is

Options

A. `mg + (3F)/(4)`
B. `mg - (3F)/(4)`
C. `mg + (4F)/(3)`
D. `mg - (4F)/(3)`

Answer

C

Explanation

If both the block are stationary.
balancing forces along x-direction
`F = N sin theta implies N = F // sin theta`
balancing forces along y-direction
`N_(y) = mg + N cos theta = mg + ((F)/(sin theta)) cos theta = mg + F cot theta`
`N_(Y) = mg + (4F)/(3)`