Question

Whenever a body is in motion, there is always_________ to oppose the motion.

Answer 1

1. The frictional force is a force that always resists the motion of one body over another in contact with it.

Properties of frictional force:

1. Frictional force always acts parallel to two planes in contact with one other and in the opposite direction of the two bodies' relative motion.
2. Intermolecular interactions between the substances create frictional forces.
3. Frictional force reduces the relative velocity of two bodies or surfaces.
4. The frictional force is greater on a rough surface and lowers on a smooth surface.

Hence, whenever a body is in motion, there is always friction to oppose the motion.