A 8.00-cm-long wire is pulled along a U-shaped conducting rail in a perpendicular magnetic field. The total resistance of the wire and rail is 0.310 ohms . Pulling the wire at a steady speed of 4.0m/s causes 3.80W of power to be dissipated in the circuit.
PART A: How big is the pulling force?
PART B: What is the strength of the magnetic field?