A plastic circular loop of radius R and a positive charge q is distributed uniformly around the circumference of the loop. The loop is then rotated around its central axis, perpendicular to the plane of the loop, with angular speed w. If the loop is in a region where there is a uniform magnetic field B directed parallel to the plane of the loop, calculate the magnitude of the magnetic torque on the loop.
An iron block of 20 kg undergoes a process during which there is a heat loss from the block at 4 kJ/kg, an elevation increase of 50 m, and an increase in velocity from 10 m/s to 50 m/s. During the process, which also involves work transfer, the internal energy of the block decreases by 100 kJ. Determine the work transfer during the process in kJ if the total energy remains constant. Include sign.
