A cement block with a mass of 5.0 kg is at rest on a horizontal floor.

A force of 21 N [E] starts the block moving. Find the coefficient of static friction for the block and floor.

1 answer

The force of friction can be calculated using Newton's second law:

F_friction = coefficient of static friction * normal force

The normal force is equal to the force of gravity acting on the block:

Normal force = mass * gravity = 5.0 kg * 9.81 m/s^2 = 49.05 N

Since the block is at rest, the maximum static frictional force is equal in magnitude to the applied force:

F_friction = 21 N

Therefore, the coefficient of static friction can be calculated as:

coefficient of static friction = F_friction / normal force = 21 N / 49.05 N = 0.428

Therefore, the coefficient of static friction between the block and the floor is 0.428.