Question

A pump is required to lift a mass of 820 of water per minute from a well of depth 13.0 and eject it with a speed of 18.5 . How much power per minute?

Answer 1

Well since power is work per time, you need to find the work that the pump does. We know that work is the change of energy which in this case is given by the potential and kinetic energy given to the water. Therefore:\[P=\frac{ W }{ t }=\frac{ \Delta E }{ t }=\frac{ \frac{ 1 }{ 2 }mv ^{2}+mgh }{ t }=\frac{ \frac{ 1 }{ 2 }820kg(18.5\frac{ m }{ s }) ^{2}+820kg9.8\frac{ m }{ s ^{2} }13m }{ 1\min \frac{ 60s }{ 1\min } }\]