Chapter 8 Multiple choice questions

. Section 8.2 describes the petrol or spark ignition engine. Box 8.1 and Figure 8.2 describe the combustion process in a four-stroke internal combustion engine. What happens on the induction stroke?

The air-fuel mixture burns rapidly.

Fuel and air are drawn into the cylinder.

The air-fuel mixture is compressed.

The burned gases are pushed out of cylinder.

. Box 8.2 on pages 273-274 describes power and speed. A cyclist on a flat road is travelling at 5 metres per second (11 mph). He weighs 80 kg and his bicycle another 20 kg. If he has to stop within 5 seconds, what will be the rate at which the cycle's brakes must dissipate heat?

250 watts

100 watts

500 watts

. What does the 'octane rating' of petrol indicate?

Its energy content per litre

Its ability to withstand compression without spontaneously igniting

Its sulfur content

. Section 8.3 describes the diesel engine. Those in cars typically rotate at up to 4000 revolutions per minute (r.p.m). How fast do the diesel engines in the largest container ships rotate?

About 2000 r.p.m.

About 500 r.p.m.

About 100 r.p.m.

. Section 8.4 describes reducing pollution from petrol and diesel engines. The nitrogen in the combustion air in an engine can be oxidized to the acid gas nitrogen oxide. This reaction only takes place above what temperature?

500 degrees C

1000 degrees C

1500 degrees C

. Which of the following is a method of reducing the NOx emissions of diesel engines, requiring the injection of ammonia into the exhaust gas stream?

Oxidation catalytic convertor

Exhaust gas recirculation

Selective Catalytic Reduction

. Section 8.5 describes the gas turbine. Box 8.4 describes the principles of the turbojet engine. The turbine blades must be capable of surviving high temperatures. What are they coated with to enable this?

Silicon-based ceramics

Iron oxide

Calcium carbonate

. Jet engines propel an aircraft forwards by producing a stream of fast-moving gas moving backwards. The phrase 'for every action there is an equal and opposite reaction' is which law of physics?

The First Law of Thermodynamics

Newton's Second Law of Motion

Newton's Third Law of Motion

. In a jet engine a large mass flow at a low velocity can produce more useful thrust than a smaller flow at a higher velocity. What component of a modern jet engine is used to achieve this?

Compressor

Bypass fan

Combustion chamber

. Section 8.6 describes the Stirling engine, which can be almost silent. Between 1937 and 1946 the Dutch Philips company developed a small portable Stirling engine generator. What was its intended use?

A supply for domestic refrigerators

An engine for small motorbikes

A power supply for domestic valve radios

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