Final answer:
Automatic expansion valves are good at maintaining constant pressure.
Step-by-step explanation:
An automatic expansion valve is good at maintaining constant pressure in a system.
In physics, pressure is defined as the amount of force applied per unit area. In the case of automatic expansion valves, they are designed to regulate the pressure in a system by adjusting the flow of a fluid or gas. This ensures that the pressure remains constant even when there are changes in other variables such as temperature or volume.
For example, in a car's tire, the automatic expansion valve helps maintain a constant pressure even when the tire volume changes due to changes in temperature or when the car is in motion.