Question

A boy pushes down on a car rolling horizontally down the road. If the boy pushes down vertically with 10 N of force as the car rolls 3.0 m horizontally, the amount of work done by the boy is:Question 1 options:3.3 Jnone of these choices-30 N·m10 J30 N·m

Answer 1

The work done by a constant force in a rectilinear motion is given by:

`W=Fd\cos\theta`

where F is the magnitude of the force, d is the magnitude of the displacement and theta is the angle between the force and the displacement vector.

In this case we know the following:

The magnitude of the force is 10 N.

The magnitude of the displacement is 3m.

The car moves horizontally and the force is pointing vertically down; this means that the angle between the force and the displacement is 90°.

With this in mind we have that the work is:

`\begin{gathered} W=(10)(3)\cos90 \\ W=0 \end{gathered}`

Therefore, the work done by the boy is zero and the correct option is none of these choices.