Question

Water is pumped out of a well 10 m deep by means of a pump rated 10KW.Find the efficiency of the motor if 4200 kg of water is pumped out every minute

Answer 1

Dear Student,

Potential Energy Gained by water in 60 sec= 4200 x 10 x 10 = 4.2 x 10 ⁵ J ( output)

Energy spend by pump( work done by pump)= P x t = 10 x 10³ x 60 = 6x 10 ⁵ J ( input)

$$\begin{gathered} Efficiency=\frac{Workoutput}{Workinput}\times 100 \\ =\frac{4.2}{6}\times 100 \\ =0.7\times 100 \\ =70\% \end{gathered}$$

Regards.