Grade 10 power mechanics – Types of Engines Quiz
1. Which type of engine uses the four stages: intake, compression, power (combustion) and exhaust?
The four-stroke engine completes the cycle in four strokes of the piston: intake, compression, power and exhaust. Two-stroke combines some stages, gas turbines work differently and electric motors do not use piston strokes.
2. What characteristic mainly distinguishes a two-stroke engine from a four-stroke engine?
A two-stroke engine completes the full cycle in two piston strokes (one crankshaft revolution). Many two-strokes mix oil with fuel and may use spark plugs (for petrol), but the defining feature is the two-stroke cycle.
3. Which engine uses compression ignition rather than a spark for ignition?
Diesel engines compress air to a high temperature so fuel ignites on injection (compression ignition). Petrol engines use spark plugs; Wankel rotary is a type of petrol engine variant; steam engines are external combustion.
4. Which of these is an example of an external combustion engine?
In external combustion engines (like steam engines), fuel burns outside the working fluid chamber to create steam that then drives pistons or turbines. Diesel and petrol engines burn fuel internally.
5. Which engine type is commonly used in small motorcycles and is often air-cooled?
Small motorcycles typically use single-cylinder petrol engines that are often air-cooled. Diesel inline-six and gas turbines are used in much larger applications; Stirling engines are uncommon in motorcycles.
6. What is a key advantage of diesel engines compared to petrol engines?
Diesel engines generally have higher compression ratios, giving better thermal efficiency and fuel economy. They do not use spark plugs and run on diesel fuel, not gasoline.
7. Which engine type uses a triangular rotor moving in an oval chamber instead of pistons?
The Wankel rotary engine uses a triangular rotor turning within a roughly oval housing, producing chambers that change volume — distinct from piston engines.
8. Which component in a petrol engine produces the spark to ignite the air–fuel mixture?
Spark plugs provide the electric spark that ignites the air–fuel mixture in petrol (spark-ignition) engines. Glow plugs are used in some diesel engines for cold starting.
9. What type of engine is most commonly used to power jet passenger aircraft?
Most passenger jets use gas turbine engines (turbojets or turbofans) which compress air, mix with fuel, burn it and expel high-speed gases to produce thrust.
10. Which cooling method uses airflow over fins attached to the engine cylinder to remove heat?
Air-cooled engines have fins on cylinders and rely on airflow to dissipate heat. Liquid cooling uses coolant and a radiator instead.
11. What is the main function of a turbocharger on an engine?
A turbocharger harnesses exhaust energy to drive a turbine that compresses incoming air, increasing oxygen mass and allowing more fuel to be burned for greater power.
12. Which valve arrangement has the camshaft located above the cylinder head operating the valves directly?
OHC engines have the camshaft in the cylinder head above the valves, allowing direct or short actuation. OHV uses pushrods; side valve places valves in the block.
13. Which engine layout has cylinders arranged in a straight line along the crankshaft?
Inline engines (e.g., inline-four) have cylinders in a single straight row along the crankshaft. V-type has two banks forming a V, boxer has opposed horizontal cylinders, radial arranges cylinders around a crank.
14. Which engine type commonly uses a glow plug for starting, especially in cold weather?
Glow plugs heat the combustion chamber in diesel engines to aid cold starting because diesel relies on high compression and hot air to ignite fuel.
15. Which engine type combines an internal combustion engine with an electric motor to reduce fuel use in city driving?
Hybrid systems pair an internal combustion engine with an electric motor and battery to improve efficiency, especially in stop-start city traffic.
16. What is a key characteristic of a radial aircraft piston engine?
Radial engines have multiple cylinders mounted around a central crankshaft like spokes, commonly used in older aircraft designs.
17. Which engine type often mixes oil with the petrol for lubrication rather than having a separate oil sump?
Many two-stroke engines mix oil into the fuel to lubricate moving parts because they lack a separate oil sump. Four-stroke engines use a crankcase oil sump.
18. Which engine design has two pistons in one cylinder moving toward each other with no cylinder head?
Opposed-piston engines have two pistons in each cylinder moving in opposite directions, sharing the combustion space and eliminating the cylinder head.
19. Which of the following best describes a Stirling engine?
A Stirling engine is an external combustion engine where a working gas is cyclically heated and cooled inside the engine to produce expansion and contraction, driving pistons.
20. What is the main reason petrol engines have lower compression ratios than diesel engines?
Petrol engines use spark ignition, and high compression can cause the mixture to auto-ignite (knock). Diesel uses compression ignition and therefore operates at higher compression ratios.
21. Which component is essential in a direct-injection petrol or diesel engine to deliver fuel directly into the combustion chamber?
Fuel injectors precisely spray fuel directly into the combustion chamber (direct injection) or into the intake (port injection). Carburettors mix air and fuel in older petrol engines.
22. Which engine type produces thrust by accelerating a large mass of air through a propeller driven by a turbine?
Turboprops use a gas turbine to drive a propeller; most thrust comes from the propeller moving large air mass at lower speed, suitable for short/medium-range aircraft.
23. Which engine arrangement has cylinders opposing each other horizontally and is often called a flat engine?
Boxer engines have horizontally opposed cylinders where pistons move in and out opposite each other, lowering the centre of gravity and improving balance.
24. Which of these is NOT a typical advantage of electric motors compared to internal combustion engines?
Electric motors do not burn fuel inside the motor; they use electrical energy, produce no tailpipe emissions, have immediate torque and fewer moving parts.
25. Where are overhead valve (OHV) engines commonly found compared to overhead cam (OHC) engines?
OHV (pushrod) designs are typical in older or some heavy-duty engines; OHC places the camshaft in the head and is common in modern passenger cars for better high-speed performance.
26. Which fuel system component was widely used on older petrol engines but has largely been replaced by fuel injection in modern vehicles?
Carburettors mixed air and fuel mechanically in older petrol engines; modern engines typically use electronic fuel injection for better efficiency and emissions control.