Question

When the velocity of a body is doubled, then its kinetic energy will become
(a) 8 times
(b) 4 times
(c) 16 times
(d) None of these

Answer 1

Answer:

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Answer 2

Answer:

(b) 4 times

Explanation:

Let's assume that the kinetic energy of a body is K1 , mass m and velocity be V1. Then then kinetic energy of the body is given by,

$K1\ =\ \dfrac{1}{2}\times m\times (V1)^2......(1)$

AS given in question we are increasing the velocity of the body by 2 times .So, if the kinetic energy of the body after increasing velocity is K2 and velocity is V. Then,

V2 = V1

and

$K2\ =\ \dfrac{1}{2}\times m\times (V2)^2$

$=>\ K2\ =\ \dfrac{1}{2}\times m\times (2\times V1)^2$

$=> K2\ =\ \dfrac{1}{2}\times m\times 4\times (V1)^2......(2)$

DIvide equation (2) by equation 1, we will get

K2 = 4.K1

So, the kinetic energy of the body will be 4 times when we double it velocity.