Question

A water pump lifts water from a level $10m$ below the ground. Water is pumped at a rate of $30kg/minute$ with negligible velocity. Calculate the minimum horsepower the engine should have to do this.

Answer 1

Given :-

Mass, pump Flow rate = 30 kg / min. = 30 kg / 60 s. = 0.5 kg/s.

Height h = 10 m.

we know, pump water has negligible velocity , then it's K.E is zero.

Pump work to increase the level of water above 10 m.

Now weight of the water = mg

= 0.5 × 9.8

= 4.9 N.

Now power = mgh

P= 4.9 × 10 m

P= 49 W.

Now we know 1 hp = 746 W.

So minimum power = 49 / 746

=0.066

= 6.6 × 10⁻² hp.

Hence the minimum horsepower is 6.6 x 10⁻² hp.