Chapter 11, Problem 11.32P

3. An Atwood machine consists of two masses, mA and m B, which are connected by an inelastic cord of negligible mass that passes over a pulley. If the pulley has radius RO and moment of inertia I about its axle, determine the acceleration of the masses mA and m B, and compare to the situation where the moment of inertia of the pulley is ignored. Ignore friction at the axle O. Use angular momentum and torque in this solution

A 0.850-m-long metal bar is pulled to the right at a steady 5.0 m/s perpendicular to a uniform, 0.650-T magnetic field. The bar rides on parallel metal rails connected through a 25-Ω, resistor (Figure 1), so the apparatus makes a complete circuit. Ignore the resistance of the bar and the rails.  Please explain how to find the direction of the induced current.

For each of the actions depicted, determine the direction (right, left, or zero) of the current induced to flow through the resistor in the circuit containing the secondary coil. The coils are wrapped around a plastic core. Immediately after the switch is closed, as shown in the figure, (Figure 1) in which direction does the current flow through the resistor? If the switch is then opened, as shown in the figure, in which direction does the current flow through the resistor? I have the answers to the question, but would like to understand the logic behind the answers. Please show steps.