I think I solved the problem. Emf = BLV. And we know that emf will be equal to IR when the current is 0.5A.
0.5 x 9 = 4 x 1.2 x V
Therefore the velocity equals 0.9375 m/s.
Is this correct?
I have attached a copy of the question I am having issues with, I can't seem to figure out the equation I have to use to solve this. My lecturer did an example of this but for some reason I can't find it anywhere.