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How work done = difference between k.e
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Asked by swainanirudha1 | 12 Nov, 2018, 11:52: PM
answered-by-expert Expert Answer
Let us assume an object of mass m is subjected to a force of F .
Let, due to this action of force,  the object has changed its initial speed vi to vf  and moved to a distance S in time t.
 
We know the wrokdone W = Force×distance = F×S ......................(1)
 
force F = mass × acceleration = mass × (change in speed ) / time = m×(vf - vi)/t  ......................(2)
 
distance S = (average speed)×time = [ (vf + vi) / 2 ]×t  ......................... (3)
 
If we substitute for F and S in eqn.(1), using eqns.(2) and (3), we get,  W = F×S = (1/2)×m×(vf2 - vi2 ) ...................(4)
 
Hence from eqn.(4), it is proved that Workdone = Change in kinetic energy
Answered by Thiyagarajan K | 13 Nov, 2018, 06:21: AM

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