# What is the work Ww done on the box by the weight of the box?

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A box of weight w=2.0N accelerates down a rough plane that is inclined at an angle ϕ=30∘ above the horizontal, as shown (Figure 6) . The normal force acting on the box has a magnitude n=1.7N, the coefficient of kinetic friction between the box and the plane is μk=0.30, and the displacement d⃗ of the box is 1.8 m down the inclined plane.

A box of weight w=2.0N accelerates down a rough plane that is inclined at an angle ϕ=30∘ above the horizontal, as shown (Figure 6) . The normal force acting on the box has a magnitude n=1.7N, the coefficient of kinetic friction between the box and the plane is μk=0.30, and the displacement d⃗ of the box is 1.8 m down the inclined plane.

##### 1 Answer

OK, first we need to find the force pulling the box down the plane, then figure out the work done.

#### Explanation:

The friction is given by

So *against* the motion, so acts *up* the plane.

The force acting down the plane is given by the component of gravity acting parallel to the plane,

So the net force,

Work done, W = F.s

So

Thus W = 0.882 or 0.88 Nm to 2 s.f.