Answer
$v=6.3\times 10^3m/s$
Work Step by Step
First, calories must be converted to joules using dimensional analysis. $$210 kCal \times \frac{4184J}{1kCal}=8.8\times 10^5J$$ Use the formula for kinetic energy $$K=\frac{1}{2}mv^2$$ to solve for velocity $v$. $$v=\sqrt{\frac{2K}{m}}$$ Substituting known values of $K=8.8\times 10^5J$ and $m=0.045kg$ yields a velocity of $$v=\sqrt{\frac{2(8.8\times 10^5 J)}{0.045kg}}=6.3\times 10^3m/s$$
