A conductingng bar of mass 1. w kg and length l = 1. x m is placed at rest on a frictionlsss plane inclined at an angle θ = 2 y degrees to the horizontal. A current I= 4 A flows through the bar in the − ˆj direction, and there is a uniform magnetic field B = 1 T in the kˆ direction. (a) What is the gravitational force on the bar acting down the plane? (3) (b) What is the magnetic force on the bar acting up the plane? (3) (c) If the bar is initially at rest, how far does it move along the plane in 0.5 s and specify whether it moves (4) up or down. (Assume zero friction so that the bar slips rather than rolls along the plane. Rolling motion would be more complicated since rotational kinetic energy would need to be factored into the calculations.) Ok, so I calculated the gravitational force acting down the plane to be mgSin(theta). That was fine. I then calculated the Magnetic force acting up the plans but it's apparently incorrect. I crossed L(I) x B and got 4.8(-j) x 1k and got -4.8i as the force in the -I direction, (sort of into the plane). I then said that cos(theta) =h/a, the adjacent in the case being the 4.8i. I found h to be 5. something or other. It's marked as incorrect though. Any ideas?