Q. 44.5( 2 Votes )

# When the speed of a moving object is doubled, its :

A. acceleration is doubled

B. weight is doubled

C. kinetic energy is doubled

D. kinetic energy increases 4 times

Answer :

Kinetic energy KE of a body of mass m moving with velocity or speed v is given by the formula:

KE_{1} = mv_{1}^{2}

If the speed of particle is doubled then

KE_{2} = mv_{2}^{2} where, v_{2} =v_{1}

Substituting the value of v_{2} in the formula,

KE_{2} = m (2v_{1})^{2}

= (4 mv_{1}^{2})

**KE _{2} = 4 KE_{1}**

So kinetic energy will become 4 times if the speed is doubled.

On other hand, acceleration depends on final as well as initial velocity, and here acceleration will be same.

Weight is independent of change in speed.

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