Problem: A 60.0 cm long bar can slide without friction along the long horizontal fails shown in Figure 2432. The bar and the rails have a resistance of 5.00 I), and the entire setup is placed in a uniform magnetic field of 3.00 mT. (a) Derive an expression for the force needed to move the bar to the left at a constant speed. (in) Use the expression you derived in part (a) to nd the Force required to pull the bar with a constant speed of 1.5 m/s. (c) Derive the expression for the energy delivered to the resistor in 1 seconds when the bar is moving to the right with constant speed 7. (d) How much energy was delivered to the resistor when the bar was moving with a speed of1.50 m/s during 3.00 s? Fig"! 25-72 Problem 65