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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
A man spends 7.4 KJ energy in displacing a body by 74 m in the direction in which he applies force in 2.5 s. Calculate the force applied.
Name the quality which is measured in eV
State the condition when a force produces
(i) linear motion.
(ii) rotational motion, in a body.
Name the force needed for circular motion. What is the direction of the force?
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°.
1 kWh = ______ J.
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"]`
A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes. Compare:
- the work, and
- power developed by them.
Give the units of couple.
