Class 11 Physics simulations · Thermodynamics

Petrol engine (Otto cycle)

Compress the fuel–air mixture more and the ideal efficiency rises — watch the piston and crank turn.

Open the simulation

What to notice

Efficiency depends only on compression ratio r and γ — not on how much fuel is burned.

Key relation

η = 1 − r^(1−γ)

Try this

Raise r from 8 to 12. How much does efficiency improve?

What you can change

• Compression ratio r: 2 to 14
• Heat capacity ratio γ: 1.3 to 1.67
• Engine speed: 600 to 6000 rpm

More in Thermodynamics

• Adiabatic compression and expansion
• Carnot heat engine
• First law of thermodynamics
• Heating gas at constant pressure
• Entropy in isothermal expansion
• Work from a rectangular P–V cycle
• Refrigerator and heat pump
• Gas under a piston

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