A proton with an initial velocity of (1.0x + 2.0y + 3.0z) x10^5 m/s enters a magnetic field of 0.50z T. Find the magnitude of the force on the proton. The mass of the proton is 1.67x10^-27 kg. The answer is 1.8x10^-14 N I think the equation you should use is F=qv*B We are given both B and q (1.6022*10^-19), but how do we get the velocity?