Question

A box is pushed through 4.0 m across a floor offering 100 N resistance. How much work is done by the resisting force?

Answer 1

Answer:

W = F X S

W= 100 X 4

W = - 400 J

- sign indicates resisting force is opposite in Direction

Answer 2

Work done by the resisting force is -400 J

Explanation:

Step 1:

given values  

Force = 100 N

Distance = 4 m

So we know work is done when we apply the force in such a way that the target is displaced.So, Expression for work done,

Work done (W) = Fs cosθ

Step 2:

The work done on the box as it falls is proportional to the weight of the box (a force) multiplied by the distance to the ground (a displacement) when the box is placed above the ground and then lowered.

If the force F is constant and the angle between the force and the displacement s is θ, then the work  

done is performed by W = Fs cos θ

θ = 180°

Step 3:

By substituting values,

W = 100 × 4 × cos 180°

W = 100 × 4 × (-1)

= -400 J