Power
An electric water pump raises 600 litres of water through a vertical height of 20 m every minute on a farm. Assuming no losses and taking g as 10 m/s squared, what is the minimum power output of the pump?
Select the correct option:
Solution
2000 W
As explained in NCERT Class 11, Chapter 6 (Work, Energy and Power), power is the rate of doing work, P = W/t, and for lifting water the work is the gain in potential energy mgh. Six hundred litres of water has a mass of 600 kg, since one litre of water is one kilogram. The work done per minute is W = mgh = 600 × 10 × 20 = 120000 J. This is delivered over 60 seconds, so P = 120000 / 60 = 2000 W. The option 1200 W comes from dividing by an incorrect time. The option 120000 W forgets to divide by time and gives total work, not power. The option 200 W misplaces a factor of ten. A unit check confirms joules per second gives watts, and 2000 W or 2 kW is a sensible rating for a small farm pump moving this much water each minute.
🔒 Solution Hidden from View
Submit your answer to unlock the detailed step-by-step solution.
More power Practice Questions
A cyclist of total mass 70 kg rides up a slope inclined at 30 degrees to the horizontal at a steady ...
A cyclist of total mass 70 kg rides up a slope inclined at 30 degrees to the horizontal at a steady ...
A weightlifter raises a barbell of mass 80 kg from the floor to a height of 2 m above the floor in 4...
A weightlifter raises a barbell of mass 80 kg from the floor to a height of 2 m above the floor in 4...
A car engine delivers a constant power of 50 kW while the car moves at a steady speed of 25 m/s alon...
A car engine delivers a constant power of 50 kW while the car moves at a steady speed of 25 m/s alon...
An astronomer wants a telescope to distinguish two closely spaced stars more clearly, and a student ...
An astronomer wants a telescope to distinguish two closely spaced stars more clearly, and a student ...
Two thin lenses of powers +5 D and -2 D are placed in contact along the same axis, and an optician w...
Two thin lenses of powers +5 D and -2 D are placed in contact along the same axis, and an optician w...
About This Question
- Subject
- physics
- Chapter
- work, energy and power
- Topic
- power
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
2000 W
As explained in NCERT Class 11, Chapter 6 (Work, Energy and Power), power is the rate of doing work, P = W/t, and for lifting water the work is the gain in potential energy mgh. Six hundred litres of water has a mass of 600 kg, since one litre of water is one kilogram. The work done per minute is W = mgh = 600 × 10 × 20 = 120000 J. This is delivered over 60 seconds, so P = 120000 / 60 = 2000 W. The option 1200 W comes from dividing by an incorrect time. The option 120000 W forgets to divide by time and gives total work, not power. The option 200 W misplaces a factor of ten. A unit check confirms joules per second gives watts, and 2000 W or 2 kW is a sensible rating for a small farm pump moving this much water each minute.
This medium difficulty physics question is from the chapter work, energy and power, covering the topic of power. It appeared in the 2025 exam.
Looking for more practice? Explore all physics questions or browse work, energy and power questions on RankGuru.