A tow rope, parallel to the water, pulls a water skier directly behind a boat with constant velocity for a distance of $65 \mathrm{~m}$ before the skier falls. The tension in the rope is $120 \mathrm{~N}$. (a) Is the work done on the skier by the rope positive, negative, or zero? Explain. (b) Calculate the work done by the rope on the skier.