Answer
$4.37 \times 10 ^{4} m/s$
Work Step by Step
By the conservation of energy;
Loss in energy = Gain in energy
$q \Delta V=\frac{1}{2}m_{p}v_{p}^{2}$
$v_{p}=[\frac{2q\Delta V}{m}]^{1/2}$
$v_{p}=[\frac{2\times 1.6 \times 10^{-19} \times 10^{3}}{1.67\times 10^{-27}}]^{1/2}= 4.37 \times 10 ^{4} m/s$
