Question

A smooth block A rests on a horizontal plank. The angle of inclination of the plank with horizontal is gradually increased from 0 degrees to 90°. Then, a. the normal reaction between plank and block gradually decreases up to zero b. the normal contact force between wall and the block gradually increases up to mg c. the normal contact force between the wall and block is always zero d. the normal contact force between the plank and block gradually increases up to mg​

Answer 1

Answer:

i don't know its confusion i

Answer 2

Answer:

a) The normal reaction b/w plank and block decreases to zero.

b) The normal reaction b/w wall and block gradually increases to mg.

Explanation:

a) The normal reaction force occurs when force is applied on plank by block as angle is increased to 90, the block will no longer exert force on the plank due to it's weight as it acts only in the downward direction.

b) The opposite happens b/w the wall and block.

Hope it is helpful...