A proton enters a uniform magnetic field that is at a right angle to its velocity. The

Question:

A proton enters a uniform magnetic field that is at a right angle to its velocity. The field strength is 0.80 T and the proton follows a circular path with a radius of 4.6 cm. What are
(a) The magnitude of its linear momentum and
(b) Its kinetic energy?
(c) If its speed were doubled, what would then be the radius, momentum, and kinetic energy?