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प्रश्न
What is the S.I. unit of work? Define it.
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उत्तर
The S.I. unit of work is newton-metre or joule (J).
1 Joule = 1 N × 1 m.
1 J of work is said to be done by a force of 1 N if it displaces a body by 1 m in the direction of the force.
संबंधित प्रश्न
When does a force do work?
Name the quality which is measured in kW.
What is meant by a rotatory motion? Give one example.
State the factors on which moment of force about a point depends.
In which one of the following cases is the work done more? When the angle between the direction of motion and that of the force is (i) 90° (ii) 0°.
State the condition when the work done by a force is negative. Explain with the help of examples.
A pump is used to lift 600 kg of water from a depth of 75 m in 10s. Calculate:
- The work done by the pump,
- the power at which the pump works, and
- The power rating of the pump if its efficiency is 40%. (Take g = 10m s-2).
`["Hint" : "Efficiency" = "useful power"/"power input"]`
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A man raises a box of mass 50 kg to a height of 2 m in 20 s, while another man raises the same box to the same height in 50 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1
