A small block of mass `m` is released from a fixed smooth wedge in figure. Initial point is marked as `A`. Bottom of wedge is marked as `B` and at a point `C` the block stops because the straight part of floor is rough.

Work donw by normal reaction is zero during the motion of the block

Options

A. from point `A` to `B` only
B. from point `B` to `C` only
C. from `A` to `C`
D. none of these

Answer

C

Explanation

The normal reaction is always `_|_` to surface and the displacement is always along the surface.
`:. ` froce and displacement are `_|_` to each other . From `A` to `C` it is zero.