A Proton Is Accelerated from Rest Through 0

Short Answer

A proton is accelerated from rest through 0.50 kV. It then enters a uniform magnetic field
of 0.30 T that is oriented perpendicular to its direction of motion.
(a) What is the radius of the path the proton follows in the magnetic field?
(b) How long does it take the proton to make one complete circle in the magnetic field?.