Friction braking of a motor is normally controlled by a(n) ___.

Friction braking of a motor is typically controlled by a solenoid because it operates by applying a mechanical force that engages the braking mechanism directly. When the solenoid is energized, it moves a plunger that engages the brake pads, creating friction that slows down or stops the motor. This method is efficient for quick stopping and is commonly used in various applications where rapid braking is essential.

In contrast, pushbuttons are primarily used for starting or stopping motors rather than directly controlling braking. Transformers are used to change voltage levels and do not play a role in braking systems. Contactors, while they control the flow of electricity to a motor, do not directly engage a braking mechanism. Thus, the solenoid’s role in providing direct mechanical action makes it the appropriate choice for controlling friction braking in motors.