Question

A block is sliding down a fixed inclined plane as shown below.


The direction of frictional force acting on the block is:

• A. Vertically downwards
• B. Vertically upwards
• C. Downwards along the inclined plane
• D. Upwards along the inclined plane

Answer 1

The correct option is D Upwards along the inclined plane

Friction opposes relative motion between two bodies in contact.
It acts in direction so as to oppose the relative motion between the objects.
As the block is sliding down the inclined plane, friction will act upwards along the plane to oppose the motion of the block.