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प्रश्न
State two conditions for work to be done.
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उत्तर
The two conditions are:
(i) Application of-force on the body.
(ii) Displacement of the body in the direction of the force.
संबंधित प्रश्न
When does a force do work?
A satellite revolves around the earth in a circular orbit. What is the work done by the force of gravity? Give reason.
One horse power is equal to ______.
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 man raises a box of mass 50 kg to a height of 2 m in 20s, while another man raises the same box to the same height in 50s. Calculated:
- the work done, and
- the power developed by each man. Take g = 10 N kg-1.
Justify the statement. “Power can be expressed as the product of force and velocity.”
State the practical unit mainly used in mechanical engineering and write down its equivalent in watt.
Calculate the work done when:
A car is moved on a rough road through 30 m against a frictional resistance of 75 N.
A machine raises a load of 750 N through a height of 16 m in 5 seconds. Calculate the power at which the machine works.
