Answer
The kinetic energy increases by 56%
Work Step by Step
Kinetic energy has units of $kg~m^2~s^{-2}$
Velocity has units of $m~s^{-1}$
Therefore, we need to square the velocity to find the kinetic energy.
We also need to include mass $m$ since kinetic energy includes units of $kg$.
Then $KE = C~m~v^2$, where $C$ is some constant.
$\frac{KE'}{KE} = \frac{C~m~(v')^2}{C~m~v^2} = \frac{(1.25v)^2}{v^2} = 1.56$
The kinetic energy increases by 56%.
