🔍 Key Concepts

• Thermal expansion of liquids when heated • Behavior of hydraulic fluid in a closed system • Relationship between temperature, volume, and pressure for (nearly) incompressible fluids

💭 Think About

• Think about what usually happens to most liquids when their temperature rises: do their molecules move closer together or farther apart? • In a hydraulic system, if temperature rises and pressure is held about the same, what general change in volume would you expect? • Eliminate the options that describe behavior opposite to normal thermal expansion of liquids.

✅ Before You Answer

• Recall that most hydraulic fluids are treated as nearly incompressible—pressure changes have very little effect on their volume. • Focus on how temperature alone affects volume, not on what might happen if both temperature and pressure were changing in opposite ways. • Check which answer choice best matches the normal expansion behavior of liquids when heated.