In a reciprocating heat engine, such as a basic steam engine, high-pressure hot gas is used to push against a piston to perform mechanical work. What happens to the volume and the temperature of the gas as it pushes the piston outward?
- The gas expands in volume, and its temperature decreases as thermal energy is converted into work.Answer
- BThe gas volume remains constant because fluids used to transfer physical force cannot be expanded or compressed.
- CThe gas contracts in volume because exposing a material to high heat causes it to physically shrink.
- DThe gas expands in volume, but its temperature remains perfectly constant like a material undergoing a phase change.
Answer
The gas expands in volume, and its temperature decreases as thermal energy is converted into work.
In any basic heat engine, the working fluid (a hot, high-pressure gas) generates power by expanding. As it pushes the piston outward (increasing its volume), it expends its own internal thermal energy to do that mechanical work, which inherently causes its temperature to drop.
Step-by-Step Solution
Key Concept
Heat engines operate by converting the internal thermal energy of a high-pressure gas into mechanical work through expansion, which naturally causes the gas to cool.