Question

If the speed of a car is halved, how does its kinetic energy change?

• A. Remains same
• B. Becomes quadrupled
• C. Becomes one-fourth
• D. Becomes one-half

Answer 1

The correct option is C Becomes one-fourth

$K.E=0.5m\times v^2$
If $v$ becomes $v/2$ then,
$K.E=0.5\times m\times (v/2{)}^2$
$K.E=0.5\times m\times v^2/4$
Hence K.E becomes one fourth times the original.