Electrical potential energy:
U0 = qV0
Uf = qVf
KE0 = (1/2)mv02
KEf = [(1/2)mv02]/3 = (1/6)mv02
A proton has an initial speed of 3.9 × 105 m/s.
What potential difference is required to reduce the initial kinetic energy of the proton by a factor of 3?