Question:
A motor can pump 7560 kg of water per hour from a well of depth 100 m. If the efficiency of the pump is 70%, then the power of the pump is:
A motor can pump 7560 kg of water per hour from a well of depth 100 m. If the efficiency of the pump is 70%, then the power of the pump is:
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Always include efficiency in your power calculations. It adjusts the actual power output relative to the total power input.
Updated On: Jun 6, 2025
- 4 kW
- 6 kW
- 3 kW
- 7 kW
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The Correct Option is A
Solution and Explanation
The work done by the motor is equal to the potential energy required to lift the water:
\[
W = mgh,
\]
where \(m = 7560 \, \text{kg}\), \(g = 10 \, \text{m/s}^2\), and \(h = 100 \, \text{m}\). The power is the work done per unit time:
\[
P = \frac{W}{t}.
\]
Using the efficiency of the pump, the actual power is:
\[
P_{\text{actual}} = \frac{P}{\text{efficiency}} = \frac{4 \, \text{kW}}{0.7}.
\]
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