Science
Certain force acting on a 20 kg mass changes its velocity from 5 ms-1 to 2 ms-1. Calculate the work done by the force.
Work, Energy & Power
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Answer
Given,
Initial velocity u = 5 ms-1
Mass of the body = 20 kg
Final velocity v = 2 ms-1
Initial kinetic energy
Ei = mu2
Substituting we get,
Ei = x 20 x 52
= 10 × 25
= 250 J
Final kinetic energy
Ef = mv2
= x 20 x 22
= 10 × 4
= 40 J
As, Work done = Change in kinetic energy = Ef – Ei
Work done = 40 J - 250 J
Work done = -210 J
Hence, work done by the force = -210 J.
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