Question

What is sliding friction and rolling friction.

Answer 1

When a body slides along a rough surface, the friction between the surface and the body is known as surface friction.
Example:- Sliding friction acts between the ground and a block being pulled along the ground.

When a body rolls over a rough surface, the friction between the surface and the body is known as rolling friction.
Example:- Once the wheels of a car start rolling, the point of the wheels in contact with the road tend to slip backwards and friction opposes the motion and hence acts along the road forwards which ultimately moves the car forwards. Note that a body can be moved only by external forces and hence it is rolling friction which is responsible for the motion of a car.