I've been trying to work this out for a few days now and have got nowhere, hopefully someone here can help!
In a system with a uniform electric field in the Y direction, and a uniform magnetic field in the Z direction: Find an expression for the initial velocity u, such that the particle travels in a straight line at a constant speed.
I know that F = q(E + (V x B)), but can't really see how to go about this.
Any help appreciated.