ok, i don't know what to do with something like this: (d^2R/dt^2 ) + (dR/dt) x B = 0 where the capitals are vectors (sorry i suck at latex). R is a position vector in x-y plane and B is in the z-direction. do i split this into equations for x and y directions separately and solve them? for x-direction i would get d^2x/dt^2 + (dy/dt)|B| = 0 but how do i solve this? i'm pretty sure all the DEs i've ever solved had, for example, d^2x/dt^2 and dx/dt in them, but not d^2x/dt^2 and dy/dt. or is there a quick way of doing it without having to expand the cross product? any help would be well appreciated!!