Question

A cyclotron designed to accelerate protons of mass 1.673 x 10^-27 kg to an energy of 5.5 MeV has a diameter of 9m. The charge on a proton is 1.602 x 10^-19 C. What magnetic field must be used?

I think the formula r = mv/qB should be used but i don't know how to convert 5.5 MeV to velocity (m/s) can someone tell me if I'm on the right track? and how to convert MeV to velocity? thanks a bunch!

Change the energy to joules, then set that Kenergy equal to 1/2 mv^2 to get velocity.

thannnnnksss!