Q. A 230 , 25.0-cm-diameter plastic disk is spun on an axle through its center by an electric motor. What torque must the motor supply to take the disk from 0 to 1800 rpm in 5.00 ?
Q. The magnetic field has been measured to be horizontal everywhere along a rectangular path x = 22 cm long and y = 5 cm high. Along the bottom the average magnetic field B1 = 1.3 10-4 tesla, along the sides the average magnetic field B2 = 1.0 10-4 tesla, and along the top the average magnetic field B3 = 0.4 10-4 tesla. What can you conclude about the electric currents in the area that is surrounded by the rectangular path?