A box of mass 40 kg is dragged along the floor by a rope inclined at 60° to the horizontal. The frictional force between the box and the floor is 100N and the tension on the rope is 300N. How much work is done in dragging the box through a distance of 4m?

The work done by a force is given by

$$W = F d \cos \theta$$

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

Here, $F = 300\ \mathrm{N}$, $d = 4\ \mathrm{m}$, and $\theta = 60^\circ$.

$$\cos 60^\circ = 0.5$$ $$W = (300\ \mathrm{N})(4\ \mathrm{m})(0.5)$$

$$W = 300 \times 4 \times 0.5 = 600\ \mathrm{J}$$

The work done is $\boxed{600\ \mathrm{J}}$.