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प्रश्न
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A donkey is carrying a load on its back.
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उत्तर
- While carrying a load, the donkey has to apply a force in the upward direction. But the displacement of the load is in the forward direction.
- Since displacement is perpendicular to force, the work done is zero.
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संबंधित प्रश्न
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
A car is running at a speed of 15 km h-1 while another similar car is moving at a speed of 45 km h-1. Find the ratio of their kinetic energies.
What is the work done against gravity when a body is moved horizontally along a frictionless surface?
Give an example
Electrical energy changes to heat energy.
Calculate the work done when:
A 5 kg weight is lifted 10 m vertically. (g = 9.8 m/s2)
A water pump raises 50 kg of water through a height of 25 m in 5s. Calculate the power supplied by the pump (Take: g = 10 N kg−1).
