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A time dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest, the work done by the force during the first 1 second will be

1. 9 J
2. 18 J
3. 4.5 J
4. 22 J

Correct answer: 4.5 J

Solution

With F = 6t and m = 1 kg, a = 6t so v = 3t^2; at t = 1 s, v = 3 m/s. By work-energy theorem, work = final KE = (1/2)(1)(3^2) = 4.5 J.

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