Termodinâmica e calorimetria · GCSE Physics Topic 3 (Energy & Heating)
Simulador de motor de combustão de quatro tempos
Simulador de motor de combustão interna de quatro tempos: admissão, compressão, expansão e escape
- No navegador
- Sem cadastro
- Dedução ao vivo
- Modo projetor
- Folha de exercícios A4
Janela de simulação 3D● 60 FPS
Variáveis de controle do experimento
RPM
°
Deduções e métricas em tempo real
Válvula de admissão
--
Válvula de escape
--
Sentido do pistão
--
Tempos de expansão por segundo
--
Dedução de fórmulas em tempo real
Fórmula fundamental:
--Substituição de valores:
--Estado físico: --
Exemplos clássicos e armadilhas de exame
Worked Problem
Problema: A 4-stroke engine runs at 1800 RPM. Find: 1) flywheel revs/s; 2) cycles/s; 3) power strokes/s and total strokes/s.
Derivação passo a passo:
- 1) 1800/60 = 30 rev/s. 2) 30/2 = 15 cycles/s. 3) 15 power strokes/s and 15*4 = 60 strokes/s.
Worked Problem
Problema: What are 3 main distinctions between gasoline and diesel engines in structure, intake, and ignition?
Derivação passo a passo:
- 1) Cylinder top: spark plug (gasoline) vs fuel injector (diesel). 2) Intake: fuel-air mix vs pure air. 3) Ignition: spark-ignited vs compression-ignited.
Folha de investigação em aula e exercícios
Q1. Variant 1: If only the power stroke outputs mechanical energy, what powers the other three strokes?
Answer Key: Flywheel inertia! The power stroke spins the massive flywheel, storing rotational kinetic energy that drives the piston through the other 3 strokes.
Q2. Variant 2: Detail energy conversions and internal energy changes in compression and power strokes.
Answer Key: Compression: mechanical to internal energy (work on gas increases temperature). Power: internal to mechanical energy (gas expansion cools gas).
Q3. Variant 3: Why do diesel engines achieve higher thermal efficiency than gasoline engines?
Answer Key: Diesel compresses pure air to much higher compression ratios (18:1 vs 10:1), achieving higher peak combustion temperatures and greater Carnot thermal efficiency.
Perguntas frequentes e erros comuns
What do white smoke and black smoke from an exhaust pipe indicate?
White smoke: condensing water vapor or coolant leak into cylinder. Black smoke: incomplete fuel combustion (rich mixture or air starvation, ejecting soot particles).
Why do car engines require antifreeze coolant and radiator loops?
Peak combustion temperatures exceed 2000°C. Coolant circulation prevents thermal seizure ("cylinder scoring") and oil breakdown.
Why can't a car engine start on its own if the 12V battery is completely dead?
An engine cannot self-start from standstill. The electric starter motor draws huge battery current to turn the flywheel through initial intake and compression strokes.
Can any heat engine achieve 100% thermal efficiency? What is the theoretical ceiling?
Never! The Second Law of Thermodynamics dictates wasted heat rejection. Efficiency is bounded strictly by the Carnot limit: η = 1 - T_cold / T_hot < 100%.