Work Example II

A box with a mass of 1.0 kg is moving to the right. Its initial speed is 2 m/s. After traveling 3 m, its speed is 4 m/s. In additional to the usual forces (gravity, normal, friction) there are two other forces acting on the box. One is a 5 N force that has an upward vertical component of 4 N and a component to the left of 3 N. The other force is 8 N to the right.

(a) What is the normal force?

(b) What is the coefficient of kinetic friction?

A good free-body diagram is needed here.