A Conducting Bar Moves Along Frictionless Conducting Rails Connected to a 4.00-Ω

Short Answer

A conducting bar moves along frictionless conducting rails connected to a 4.00-Ω resistor as shown in the figure. The length of the bar is 1.60 m and a uniform magnetic field of 2.20 T is applied perpendicular to the paper pointing outward, as shown.
(a) What is the applied force required to move the bar to the right with a constant speed of
6.00 m/s?
(b) At what rate is energy dissipated in the 4.00 Ω resistor?