Question

When drawing a free-body diagram for an object on an inclined surface, which way does the friction force point?

A. Perpendicular to the surface
B. Parallel to the surface
C.Straight up
D.Straight Down

Answer 1

B. Parallel to the surface. Specifically parallel and opposite of the motion of the object.

Answer 2

B. Parallel to the surface.

Step-by-step explanation:

The friction force (static or kinetic) is a type of force that is always opposed to the move direction. Due to the move of body in an inclined surface is parallel to it, the friction force is parallel too.