A stone is moving constantly in a horizontal motion in a uniform magnetic field in the direction pointing into the page. The field's strength is 1.7T. How fast does the stone have to move in order for it to remain moving horizontally without any vertical deviation? For this quesion, using (9.8)(mass of rock)=QvB doesn't work because there's no vertical deviation. I also tried to do mv^2/r=QvB, but since it is moving horizontally and not in a circle, that doesn't work either. Can someone help me with this question please.