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प्रश्न
Give an example
Light energy changes to electrical energy.
उत्तर
Solar cell
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संबंधित प्रश्न
Define work.
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.
State the S.I. unit of energy.
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 boy of weight 40 kgf climbs up the 15 steps, each 15 cm high in 10 s and a girl of weight 20 kgf does the same in 5 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1.
Explain degradation of energy by taking two examples of your daily life.
Is work a scalar or a vector quantity?
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
How much work is done when a force of 2 N moves a body through a distance of 10 cm in the direction of force?
How many watts equal one horse power?
Why is the work done on an object moving with uniform circular motion zero?
Choose one or more correct alternatives.
For work to be performed, energy must be ______.
- transferred from one place to another
- concentrated
- transformed from one type to another
- destroyed
An object is dropped from a height H. when is its
(i) P.E. maximum,
(ii) K.E. maximum,
(iii) P.E. = K.E.?
Define energy and state the unit of energy and the law of conservation of energy.
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).
An electric motor pump is 60% efficient and is rated 2.5 H.P. Calculate the maximum load it can lift through a height of 10m in 8 sec. (1 H.P. = 750 W).
________ is said to be done when a force is acting on it.
A force can cause an object to change its ______.
