A pump is required to lift `1000kg` of water per minute from a well `20m` deep and eject it at a rate of `20ms^-1`.
a. How much work is done in lifting water?
b. How much work is done in giving in KE?
c. What HP(horsepower) engine is required for the purpose of lifting water?

Explanation

Work done in lifting water = gain in PE(potential energy)
Work = `1000 xx g xx 20 = 1.96 xx 10^(5)J` per minute.
Work done (per minute) in increasing its `KE = 1/2 mv^(2) = 1/2 (1000)(20)^(2)`
` = 2 xx 10^(5) J` per minute
Power of the engine = work done per second
` 1/60(1.96 + 2) xx 10^(5) J = 6.6 xx 10^(3)` W(watt).
Since 1 HP = 746 W, HP required = 8.85