Answer
$2.72\times 10^{-18}cal$
Work Step by Step
We know that
$KE=\frac{1}{2}mv^2$
We plug in the known values to obtain:
$KE=\frac{1}{2}(9.11\times 10^{-31})(5.0\times 10^6)^2=1.13\times 10^{-17}J$
$KE=1.13\times 10^{-17}\times \frac{1cal}{4.18J}=2.72\times 10^{-18}cal$