physics question, need help!!?

Question

A 24-N horizontal force is applied to a 40-N block initially at rest on a rough horizontal surface. If μs = 0.5 and μk = 0.4, the frictional force on the block is:

Answer 1

The weight is 40 N, therefore the normal reaction N is also 40 N.

The static frictional force f = μs*N = 0.5*40 = 20 N.

Once the block starts to move, the kinectic frictional force is f = μk*N = 0.4*40 = 16 N

Answer 2

20 N