Question

If the speed of a motor car becomes six times, then the kinetic energy becomes

• A. 6 times
• B. 36 times
• C. 12 times
• D. 24 times

Answer 1

The correct option is B 36 times

Kinetic energy, K.E = $\frac{1}{2}$mv${}^2$

If speed becomes 6 times, then

New K.E = $\frac{1}{2}$m (6v)${}^2$ = $\frac{1}{2}$m x 36 v${}^2$ = 36 x ($\frac{1}{2}$mv${}^2$) = 36 x K.E

Hence, kinetic energy becomes 36 times.