Final answer:
Mechanical or hydraulic devices that regulate the speed of a machine are called governors. They control the flow or output of a machine by adjusting the input based on changes in speed or load.
Step-by-step explanation:
Mechanical or hydraulic devices that regulate the speed of a machine are called governors. A governor is a mechanism that controls the flow or output of a machine, such as an engine, by regulating the speed or power. It does this by adjusting the input to the machine based on changes in speed or load.
For example, in a car engine, a governor can maintain a steady speed by adjusting the amount of fuel delivered to the engine. In a hydraulic system, a governor can control the flow of fluid to regulate the speed and power of a machine.
Overall, governors play a crucial role in maintaining the desired speed and performance of various mechanical and hydraulic systems.