Question

A parent pulls a young child in a sled through the snow at a constant velocity of 1.7 m/s by pulling on a rope attached to the sled with a tension of 150 N.  If the rope is pulled at an angle of 40° from the ground and the mass of the sled and the child is 39 N, how much power does the parent exert to pull the sled for one minute?

Answer 1

The power is force time speed:

$$P=Fv,\\ F=T\cos\theta,\\ P=T\cos40°·v=150\cos40°·1.7=195\text{ W}.$$