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प्रश्न
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उत्तर १
The law of conservation of energy states that energy cannot be created or destroyed; the sum total of energy in a closed system remains unchanged. Energy only changes from one form to another.
उत्तर २
According to the law of conservation of mechanical energy, the sum of kinetic energy and potential energy always remains constant.
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संबंधित प्रश्न
A boy weighing 40 kgf climbs up a stair of 30 steps each 20 cm high in 4 minutes and a girl weighing 30 kgf does the same in 3 minutes. Compare:
- The work done by them.
- The power developed by them.
When a body is placed on a table top, it exerts a force equal to its weight downwards on the table top but does not move or fall
1) Name the force exerted by the table top
2) What is the direction of the force?
Draw a simplified diagram of a lemon crusher, indicting of load and effort
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°.
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.
A coolie carrying a load on his head and moving on a frictionless horizontal platform does no work. Explain the reason why.
State the C.G.S. unit of work. How it is related to its S.I. unit?
