A box of mass m is sliding along ahorizontal surface.
Part A The box leavesposition x=0 with speed v0. The boxis slowed by a constant frictional force until it comes to rest atposition x=x1.

Find the magnitude of the average frictional force thatacts on the box. (Since you don't know the coefficient of friction, don't include it in your answer.)Express thefrictional force in terms of m, v0, x1

Part B After the box comes to rest atposition x1, a person starts pushing the box, givingit a speed v1.
When the box reaches position x2(wherex2 > x1), how much work has the person done on thebox?Assume that the box reaches x2 afterthe person has accelerated it from rest to speedv1.Express the work in terms ofm, v0, x1, x2, v1