Question

If the speed of an object is doubled then its kinetic energy

• A. is doubled
• B. becomes four times
• C. is halved
• D. is tripled

Answer 1

The correct option is B becomes four times

$KE=\frac{1}{2}m{v}^2$
Given, $v^{\prime }=2v$
$K{E}^{\prime }=\frac{1}{2}m{v}^{\prime 2}$$=\frac{1}{2}m\times 4\times v^2$
From the above two equations we get:
$K{E}^{\prime }=4\times KE$
Hence, kinetic energy is quadrupled.