# Power of a pump

by duke_nemmerle
Tags: power, pump
 P: 48 1. The problem statement, all variables and given/known data Water is pumped steadily out of a flooded basement at a speed of 5.0 m/s through a uniform hose of radius 1.0 cm. The hose passes out through a window 3.0m above the waterline. What is the power of the pump? 2. Relevant equations 3. The attempt at a solution I actually correctly solved the problem by taking advantage of the fact that $$P = \frac{\Delta W}{\Delta t }$$ which for us is $$P = \frac{\Delta m}{\Delta t} (gh + \frac{1}{2}v^{2})$$ My question is, if the force applied is constant, why can't I use $$P = \frac{F\Delta d}{\Delta t}$$ since it's a simple matter of finding the force and $$\frac{\Delta d}{\Delta t} = v$$ is given.