On tripling the speed of motion of a body, the change in K.E. is:
(a) 9 times
(b) 8 times
(c) 4 times
(d) 2 times

Academic Physics NCERT Class 9

As known, kinetic energy $K.E.=\frac{1}{2}mv^2$

On tripling the speed, the kinetic energy $K.E.=\frac{1}{2}\times m\times (3v)^2$

$=9\times \frac{1}{2}mv^2$

$= 9\times K.E.$

Therefore, the kinetic energy becomes 9 times on tripling the speed of the body.

Therefore, option (a) is correct.

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Updated on: 10-Oct-2022

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