Question

A ball moves along a smooth metal surface while an identical ball moves along concrete.

Answer 1

Answer:

2. The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.

Explanation:

Frictional force is a force that is exerted between two surfaces in contact with each other. Frictional force always opposes the direction of relative motion of the two surfaces: for instance, for a ball moving along a surface, the force of friction exerted by the surface on the ball points opposite to the direction of motion of the ball.

The magnitude of the frictional force for a ball moving on a flat surface is given by

$F=\mu mg$

where

$\mu$ is the coefficient of friction

m is the mass of the ball

g is the acceleration of gravity

The value of $\mu$ depends on the type of surface involved. In particular, a smooth surface has a smaller value of $\mu$, while a rough surface will have a bigger value. In this case, we are comparing a smooth metal surface with concrete: since the metal surface has fewer bumps and irregularities than concrete, it has a smaller value of coefficient of friction, so it exerts less frictional force than concrete.