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प्रश्न
Give two examples of work done.
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उत्तर
Examples of work done:
(i) In free fall of a body of mass m, under gravity from a height h, the force of gravity (F=mg) is in the direction of displacement (=h) and the work done by the gravity is mgh.
(ii) A coolie lifting a load does work against gravity.
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संबंधित प्रश्न
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
A weight lifter lifted a load of 200 kgf to a height of 2.5 m in 5 s. Calculate:
- the work done, and
- the power developed by him. Take g = 10 N kg-1
The power of a motor is 40 kW. At what speed can the motor raise a load of 20,000 N?
A boy does work when he pushes against a brick wall. (yes/no).
What is the work done against gravity when a body is moved horizontally along a frictionless surface?
Fill in the boxe to show the corresponding energy transformation.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
Food grains are getting dried in the sun.
