Case 1: If you take a ball and push it so that it rolls across a smooth, cemented floor. Wait for the ball to stop by itself. Mark the point at which it stopped by drawing a line on the floor with chalk powder. Measure the distance travelled by the ball using a measuring tape.
Case 2: If you take the same ball and push it the same way as before on a sandy ground. Again, measure the distance travelled by the ball.

What do you understand about frictional force in this case?

Explanation

The magnitude of frictional force between two rough surfaces is greater than that between two smooth surfaces. This is because rough surfaces have more irregularities on them as compared to smooth surfaces. The more the irregularities, the better is the interlocking between them and the more is the force required to break these interlocks. Thus, frictional force depends on the nature of surface.