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An engine pumps water through a hose pipe.Water passes through the pipe and leaves it with a velocity of 2 m/s. The mass per unit length of water in the pipe is 100 kg/m. What is the power of the engine?
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- 400 W
- 200 W
- 100 W
- 800 W
Correct Option: D
Amount of water flowing per second from the pipe
| = | = | . | = |  |  | v | ||||
| time | l | t | l |
Power = K.E. of water flowing per second
| = | | | v . v2 | |||
| 2 | l |
| = | | | v3 | |||
| 2 | l |
| = | × 100 × 8 = 400 W | |
| 2 |
