A proton moves in a circular orbit with a radius of 65 cm that is perpendicular to a uniform magnetic field of magnitude 0.75 T. What is the orbital period for the motion? What is the speed of the proton? What is the kinetic energy of the proton?

First, apply Newton’s second law to the orbiting proton to relate its speed to its radius. After, use the definition of its period (T) to eliminate r and calculate a value for T. Then find the relationship between it's period and velocity to determine v. Lastly, once the speed is known, use the definition of kinetic energy.