A box of books weighing 290 N is shoved across the floor of an apartment by a force of 400 N exerted downward at an angle of 35.0° below the horizontal. If the coefficient of kinetic friction between box and floor is 0.57, how long does it take to move the box 3.80 m, starting from rest?

Answer 1

Calculate the acceleration rate, a, using Newton's second law:

Fnet = M a

Then get the required time t using

3.80 m = (a/2) t^2

The net force Fnet is the difference between 400 N and the friction force.