# A truck pulls boxes up an incline plane. The truck can exert a maximum force of #3,200 N#. If the plane's incline is #(5 pi )/8 # and the coefficient of friction is #3/7 #, what is the maximum mass that can be pulled up at one time?

##### 1 Answer

#### Answer:

#### Explanation:

We're asked to find the maximum mass a truck can pull up at one time, with some given information.

We'll treat the boxes as *one body*, and our goal is finding the mass of this body,

The maximum mass the truck can pull is the largest so that the net force is not *down* the incline (then the boxes would not be going up, intuitively). Thus, at this condition, the boxes are in **equilibrium** (no net forces acting, pulls upward with constant velocity).

Thus, treating the positive *up* the incline:

Divide all terms by the mass,

Therefore,