A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The normal reaction force exerted by the plane on the block is directed
A) parallel to the plane in the same direction as the movement of the block.
B) parallel to the plane in the opposite direction as the movement of the block
C) perpendicular to the plane.
D) toward the center of the Earth.
E) toward the center of mass of the block.

Question

Quizplus · Accepted Answer

The normal reaction force is always perpendicular to the surface of contact between two objects. In this case, it is perpendicular to the inclined plane.

A Block of Mass M Slides Down a Frictionless Plane