Proton Speed in Constant Magnetic Field

[jan2905]

Traveling at an initial speed of 1.5x10^6m/s, a proton enters a region of constant magnetic field of magnitude 1.5T. If the proton's initial velocity vector makes an angle of 30 deg with the magnetic field, what is the proton's speed 4s after entering the magnetic field?



Not sure what equations to use.



I said that the speed did not change. Sure the path did...

 

[Redbelly98]

You're correct, the speed does not change in a magnetic field.