Solution to task 468 from Chertov´s for extramural stud

Solution to task 468 from Chertov´s for extramural stud

468. A straight conducting rod l = 40 cm long is placed in a uniform magnetic field (B = 0.1 T). The ends of the bar are closed by a flexible wire outside the field. The resistance of the entire circuit is R = 0.5 Ohm. What power P is required to move the rod uniformly perpendicular to the lines of magnetic induction at a speed of v = 10 m / s?