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Question:

A particle moves in one dimension from rest under the influence of a force that varies with the distance travelled by the particle as shown in the figure. The kinetic energy of the particle after it has travelled 3m is?

6.5 J

2.5 J

4 J

5 J

Solution:

Correct option is A. 6.5 J
According to work energy theorem
Work done by force on the particle = Change in KE
Work done = Area of F-x graph = ∫F.dx = 2×2 + (2+3)×1/2
W = KEfinal - KEinitial = 6.5
KEinitial = 0
KEfinal = 6.5 J.