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प्रश्न
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उत्तर
K.E ,K = `1/2`mv²
If speed is doubled;
K.E , K = `1/2` m (2v)²
or K' = 4 x `1/2` mv² = 4K
Thus K.E becomes four times
Thus if initially the K.E is 5J after increasing the speed twice, its k.E will become 4 x5 = 20 J.
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संबंधित प्रश्न
Define 1 J of work.
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?
A man lifts a mass of 20 kg to a height of 2.5 m. Assuming that the force of gravity on 1 kg mass is 10 N, find the work done by the man.
A cricket ball is thrown up from the earth's surface. What happens to its P.E.
(a) during the motion
(b) at the highest point?
What should be the characteristic of a source of energy?
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A wind-mill is lifting water from a well.
