Question

5. Water is pumped out of a well 10 m deep by means
of a pump rated at 10 kW. Find the efficiency of the
motor if 4200 kg of water is pumped out every
minute. Take g = 10 ms.
00/​

Answer 1

Answer:

70%

Explanation:

Power = 42x10³x10/60 = 7kw

efficiency of the  motor = 7/10 x 100% = 70%

Answer 2

Answer:

70%

Explanation:

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)

Efficiency= Work outputWork input×100=4.26×100=0.7 × 100=70 %Efficiency= Work outputWork input×100=4.26×100=0.7 × 100=70 %

Regards