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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 man having a box on his head, climbs up a slope and another man having an identical box walks the same distance on a levelled road.
Who does more work against the force of gravity and why?
What are the S.I. and C.G.S units of work? How are they related? Establish the relationship.
What do you mean by equilibrium of a body?
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°.
Justify the statement. “Power can be expressed as the product of force and velocity.”
State the S.I. and C.G.S. units of energy. How are they related?
A coolie carrying a load on his head and moving on a frictionless horizontal platform does no work. Explain the reason why.
A force of 1 kgf displaces a body by a distance of 10 cm
(i) in direction of force,
(ii) normal to the force
(iii) at an angle of 60° to the direction of the force.
Calculate the amount of work done in each case. (Take: g = 9.8 ms−2 )
For the following scenario, state whether the work done by gravity is positive, negative, or zero.
A car in neutral gear is coming down the slope.
A man raises a box of mass 50 kg to a height of 2 m in 20 s, while another man raises the same box to the same height in 50 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1
