A brass rod with a mass of 0.180 kg slides on parallel horizontal steel rails, 0.520 m apart, and carries a current of 15.0 A. The coefficient of friction between the rod and rails is 0.440. What vertical, uniform magnetic field is needed to keep the rod moving at a constant speed? (Enter the magnitude in mT.)

A brass rod with a mass of 0.180 kg slides on parallel horizontal steel rails, 0.520 m apart, and carries a current of 15.0 A. The coefficient of friction between the rod and rails is 0.440. What vertical, uniform magnetic field is needed to keep the rod moving at a constant speed? (Enter the magnitude in mT.)