An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?

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2 Answers

The object is in motion, so its energy = kinetic energy = 1 /2 mv

The kinetic energy of the object, when it comes to rest = 0. 

Work done on object = change in kinetic energy 

                                  = 1 /2 mv2 – 0 

                                  = 1 /2 mv2

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The work done on the object to bring the object to rest

= change in kinetic energy

= Final kinetic energy – Initial Kinetic energy

Here final kinetic energy is zero because the object is brought to rest.

= 0 - \(\frac{1}{2}\)mv2

= -\(\frac{1}{2}\)mv2

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