You are right, but others with a lesser grasp might try to actually find a discrete value for KE, mass, and time. By dealing with dt and friends, there is a reminder that we are dealing with infinitesimally small quantities.
It is also harder to see from the outset that one must multiply "KE...
Pinkybear's approach was flawed, because she assumed that the column of water is a perfect cylinder, which it isn't. If you look at a vertical water jet, you will see that the column thickens at it rises. This is because gravity makes the water move slower the higher it rises, and the faster...
A while ago, pinkybear posted the following:
Homework Statement
A fire hose for use in urban areas must be able to shoot a stream of water to a maximum height of 35 m. The water leaves the hose at ground level in a circular stream 3.5 cm in diameter.
What minimum power is required to create...