28. Magnetic Fields and Forces

A charged particle moving in a magnetic field experiences a force toward the top of this screen when it is moving toward the right and the field is into this screen. Is this particle positive, negative or neutral?

A rocket cruises past a laboratory at 1.00×10^6 m/s in the positive x-direction just as a proton is launched with velocity (in the laboratory frame) v =(1.41×10^6 î+1.41×10^6 ĵ) m/s. What are the proton's speed and its angle from the y-axis in (b) the rocket frame?