🔍 Key Concepts

• Diesel engine compression stroke and what happens to air in the cylinder • Relationship between pressure, temperature, and volume for a gas when it is compressed (ideal gas law) • Difference between what happens in the intake stroke vs. the compression stroke

💭 Think About

• When the piston moves up on the compression stroke, what happens to the volume of air in the cylinder? • If you squeeze a fixed amount of air into a smaller space without adding or removing heat instantly, what happens to its pressure and temperature? • Think about why diesel fuel can ignite without a spark plug—what cylinder conditions make that possible?

✅ Before You Answer

• Confirm that during compression the volume decreases while the mass of air stays the same • Apply the gas law: if volume decreases and mass stays the same, what must happen to pressure? • Then consider: when a gas is compressed quickly, what usually happens to its temperature?