A body of mass m is moving with a uniform velocity u. A force is applied on the body due to which its velocity
A body of mass m is moving with a uniform velocity u. A force is applied on the body due to which its velocity changes from u to v. How much work is being done by the force.
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Body of mass m is moving with a uniform velocity u. A force is applied on the body due to which its velocity changes from u to v and produces an acceleration a in moving a distance S. Then,
Work done by the force= force × displacement
W = F × S ---------(i)
From relation : v2 = u2+2 a S
Displacement, S = v2 - u2/2a
And force, F = ma
From equation (i), W = ma × (v2 = u2/2a)
= 1/2 m (v2 = u2)
= ki - Kl
Where K1 is the initial kinetic energy = 1/2 mu2
And K1 is the final kinetic energy = 1/2 mv2
Thus work done on the body = increase in kinetic energy
W = 1/2 m (v2 - u2)
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