A well-thrown ball is caught in a well-padded mitt. If the deceleration of the ball is $2.10 \times 10^4 \mathrm{~m} / \mathrm{s}^2$, and $1.85 \mathrm{~ms}\left(1 \mathrm{~ms}=10^{-3} \mathrm{~s}\right)$ elapses from the time the ball first touches the mitt until it stops, what was the initial velocity of the ball?