A proton, a neutron (q=+e, m = 2u) and an alpha particle (q=+2e, m = 4u), accelerated through the same potential difference, enter a region of uniform magnetic field, moving perpendicular to B. Compare their kinetic energies. If the radii of the proton's circular path is 10cm, what are the radii of the deutron's path and the alpha particle's path? u is the atomic mass unit.