A motor is used to pump water from a depth of 5 m to fill a volume of 10 cubic meters in 5 minutes. If 50% of the power is wasted, what is the power of the motor? (Assume g = 10m/s2)
Answer & explanation
Correct answer: option 4
Density of water = 1000 kg/m3
Mass of water in 10m3 = 1000 x 10
= 10000 kg
Volume of water filled in 1 s = \(\frac{10}{5*60}\)
= \(\frac{1}{30}\) m3
Mass filled in 1 s = \(\frac{1}{30}\) x 1000
= \(\frac{100}{3}\) kg
Power = \(\frac{100}{3}\) x 10 x 5; ... [As : g = 10m/s2]
= \(\frac{5000}{3}\) W
Since 50% of power is wasted, power of motor = \(\frac{5000}{3}\) x 2
= \(\frac{10000}{3}\) W.