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Work, Energy And Power

Question

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An engine pumps water through a hosepipe. Water passes through the pipe and leaves it with a velocity of 2 ms^-1. The mass per unit length of water in the pipe is 100 kgm^-1. What is the power of the engine?

400 W

200 W

100 W

800 W

Solution

D.

800 W

Power space equals space μv cubed space equals space straight m over straight l space straight x space straight v cubed space equals 100 space straight x space left parenthesis 2 right parenthesis cubed space equals space 800 space straight W

Some More Questions From Work, Energy and Power Chapter

Does the body at rest possess energy?

By eating two apples, a person starts pushing the wall of room. If food value of apple is 100 calories per apple, how much work he will do in pushing the wall in one hour?

A man is rowing upstream and is at rest w.r.t. shore. Is he doing work w.r.t. shore?

Is frictional force conservative?

What is the work done by gravitational force in taking the mass m with constant velocity through height h?

A mass is tied with a string and whirled in horizontal circle. What is the work done by tension force?

Does the work done by force depend upon the velocity at that instant?

What is the work done by man against gravity when he is carrying a load on his head and walking on the horizontal road?

Are all central forces conservative?

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