Work done in moving a proton = potential difference×Charge of a proton = 164×1.6×10⁻¹⁹ = 2.624×10⁻¹⁷ J This work done should be equal to change in kinetic energy. Initial speed of proton is zero therefore K.E initial will be zero. Work done = final kinetic energy = 2.624×10⁻¹⁷ J K.E = mv²/2 v² = 2(2.624×10⁻¹⁷)/1.6×10⁻²⁷ = 3.28×10¹⁰ m/s ∴ v = 1.811×10⁵ m/s
