A pump on the ground floor of a building can pump of water to fill a tank of volume `30 ms^(3)` in `15 min`. If the tank is `40m` above the ground and the efficiency of the pump is `30 %` , how much electric power is consumed by the pump? `("Take" g = 10 ms^(2))`

Explanation

Here, volume of water = `30ms^(3)`, t=15min = `15 xx 60=90s`
h=40m, n=`30%`
As the density of water = p = `10^(3) kg m^(-3)`
Mass of water pumped, m = volume xx density = `30 xx 10^(3)` kg
Actual power consumed or output `p_(0) = W//t = mgh//t`
`rArr p_(0)(30 xx 10^(3) xx 9.8 xx 40)//900 = 13070 watt`
If pi is input power (required), then as
`eta = p_(0)//p_(i)rArr p_(i)=p_(0)//eta` = `13070(30//100) = 43567 W = 43.56` KW