Newton's second law

The acceleration is the net force in the x direction (Fx - the frictional force) divided by the mass. Note that the coefficient of friction is assumed to be the same whether the box is stationary (static friction) or moving (kinetic friction).

Things to think about:

• What happens to the normal force as you vary the angle of the applied force?
• Can you reduce the normal force to zero? Can you have a normal force greater than the weight?
• Is the frictional force always equal to the coefficient of friction multiplied by the normal force?

Created by Andrew Duffy, Boston University Physics Department.

Last update September 15, 1998