🔍 Key Concepts

• The definition of horsepower and how it relates to power output, not pressure • The meaning of mean effective pressure in an engine cycle • The difference between compression pressure, exhaust back pressure, and pressure during the power stroke

💭 Think About

• Which term specifically describes an average pressure acting on the piston over the length of the power stroke, used in engine calculations? • Which options describe pressure conditions at other parts of the cycle (intake, compression, exhaust) rather than during the power stroke? • Which option is a measure of power (rate of doing work) rather than pressure?

✅ Before You Answer

• Identify which choice is defined in textbooks as the average pressure on the piston during the power stroke • Eliminate any term that primarily refers to engine power output instead of pressure • Eliminate terms that deal with compression or exhaust phases rather than the expansion/power phase