A desk weighing 80 N rests on the floor. The coefficient of friction between the floor and the desk is 0.25. What is the frictional force between yhe desk and the surface of the floor?

The friction force is

M*g*Uk
IF the desk is moving. Uk is the kinetic friction coefficent in this case.

The problem should have told you if the desk is moving, and whether the coefficient of friction is static or kinetic.

If the desk is not moving, the applied force equals the friction force.

To find the frictional force between the desk and the floor, we can use the equation:

Frictional force = coefficient of friction × normal force

In this case, the normal force is equal to the weight of the desk, which is given as 80 N.

Substituting the values into the equation:

Frictional force = 0.25 × 80 N

Calculating the expression:

Frictional force = 0.25 × 80 N
Frictional force = 20 N

Therefore, the frictional force between the desk and the floor is 20 N.