Associated Studies: Supporting Science

Units of measure	Multiples and decimals for the SI system	The units in the SI system are referred to as basic units.
	Length	Length is a measurement of linear distance.
	Mass	Mass is a unit or system of units by which a degree of heaviness is measured.
	Time	The metric system’s base unit of time is the second (s) while the Imperial system uses the minute (min) as its base measurement.
	Velocity	Velocity is the measurement of distance traveled over a period of time.
	Volume	Volume is the amount of space occupied by a three-dimensional object.
	Area	Area is the amount of expanse of a flat or curved surface.
	Electrical units	Basic electrical measurements are: Volts, Amperes, Ohm and Watts. All these measurements are defined by Ohm's Law.
	Pressure	Pressure is a measurement of force per unit area.
	Energy	Energy is used up when any physical system does work.
	Temperature	Temperature is the measurement of heat intensity.
	Torque	Torque is the twisting force applied to a shaft.
	Power	Power is the ability to do work.

Information & tools	Gross vehicle mass	Gross Vehicle Mass of a goods-carrying, commercial vehicle is the sum of its tare mass, and the mass of goods the vehicle can safely carry, in accordance with its design specifications.
	Hardening & tempering	By heating and then swiftly cooling certain kinds of steel changes the way that the elements in the alloy are arranged, resulting in a harder material.
	Carbon-alloy	When carbon and other materials are alloyed with iron it forms steel. The amount of carbon used can be changed effecting hardness and toughness.
	Bitumen	Bitumen is a highly viscous, black, sticky, organic liquid primarily used as a binding agent for paving roads.
	Vacuum	A vacuum or partial vacuum is the term used to describe a volume of gas with a pressure lower than atmospheric pressure. A vacuum can be created by enlarging the space containing the gas or reducing the volume of the gas in a fixed container.

Engines	Engine displacement	The total volume of air/fuel mixture an engine can draw in during one complete engine cycle.
	Electrolysis	Electrolysis is a chemical and electrical process. It occurs when two different metals are in contact, in the presence of a moist agent such as water. One of the metals is corroded away.

Engine cycles	Pressure & temperature	The pressure and temperature of a gas are linked. As pressure goes up and down, so does temperature.
	Pressure & volume	Pressure and volume are in inverse relation. As one rises, the other falls.
	Temperature & energy	The temperature of a gas is a measure of how much energy it has.
	Alloys	An alloy is a combination of materials to make a substance that has properties that are different from the original materials.
	Engine output	Engine output refers to the torque and power produced by an engine.
	Power range	The power range of an engine can be described by its 'load factor' which gives its load and speed as an average.

Engine components	Grey iron	Grey iron is a cast iron that contains carbon in the form of graphite, plus silicon, manganese and phosphorus.
	Turbulence	Turbulence refers to the swirling motion of a liquid or a gas.
	Valve-timing diagram	The time valves in a 4-stroke engine cycle actually open and close can be measured by angles. These angles can be easily read using a valve-timing diagram.
	Compression ratio	An engine’s compression ratio can be a guide to the power it can generate, the higher the engine's compression ratio and the more powerful the engine.

Engine cooling	Electrolysis	Electrolysis is a chemical and electrical process. It occurs when two different metals are in contact, in the presence of a moist agent such as water. One of the metals is corroded away.
	Centrifugal force	Centrifugal force is a force pulling outward on a rotating body.
	Thermo-switch	A thermo-switch opens and closes according to pre-set temperature levels.
	Boiling point & pressure	Changes in water pressure can change the temperature at which it boils.

Fuel systems	Bernoulli's principle	Bernoulli's principle states that in fluid flow, an increase in velocity occurs simultaneously with decrease in pressure.
	Carbon monoxide	Carbon monoxide is produced during combustion when there are not enough oxygen molecules around the hydrocarbon molecules. This can be caused by an incorrect air-fuel ratio. Carbon monoxide is an extremely poisonous gas.
	Venturi	A venturi is the name for a narrower more restricted area in a fluid passage. As fluid passes through a venturi, the fluid pressure drops and its speed increases.
	Volumetric efficiency	Volumetric efficiency is a measure of the air-fuel mixture burned in the cylinder, usually expressed as a percentage.
	Thermal expansion	Thermal expansion refers to the way some materials expand when they are heated.
	Frequency	Sound travels through the air by producing pressure waves - areas of high pressure and areas of low pressure. The rate at which these waves reach our ears is called frequency.
	Back-pressure	Back-pressure in an exhaust system refers to a build-up of pressure in the system that interferes with the outward flow of exhaust gases.
	Stoichiometric ratio	Stoichiometric ratio is the air-fuel ratio necessary for complete combustion.
	Pressure & vacuum	As air pressure is reduced, a vehicle has to reduce the amount of fuel delivered to the engine to maintain the correct air-fuel ratio.
	Air density	The density of air is its mass per unit volume.
	Tachometric relay	The tachometer indicates engine RPM.
	Potentiometer	A potentiometer is a mechanically variable resistor.
	Closed loop	A closed loop is part of a feedback system that collects information on how a system is operating & feeds that information back to affect how the system is working.

Chassis	Asbestos	Asbestos was once used in brake shoes and gaskets for its heat resistance. Asbestos fiber or powder inhalation is now known to cause some very serious respiratory diseases. As a result the use of asbestos has been banned in many countries.
	Electronic stability control	ESC monitors vehicle performance and senses when a driver is losing control, at which point it reduces the engine speed and selectively applies the brakes to individual wheels until control is regained.
	Rolling friction	Rolling friction occurs between a rolling object and the surface it is rolling on. Rolling friction effect is lower than sliding friction, but is still significant in vehicle performance.
	Traction control	Traction control is a safety feature designed to reduce wheel spin under acceleration. It works in tandem with antilock brakes and is particularly useful on loose, wet, or icy surfaces.
	Helix	The helix shape is commonly used as a thread on nuts and bolts, and also for teeth in steering gears, and transmissions.
	Unsprung weight	Parts of a vehicle not supported by the suspension system are known as unsprung weight.
	Dampening	Dampening prevents or reduces the bouncing effect of oscillation by absorbing the energy from the oscillation.
	Coefficient of friction	The coefficient of friction is the measurement of friction between pairs of surfaces.
	Lever/mechanical advantage	A lever allows small efforts to overcome large loads – or vice versa, depending on the type of lever. The ratio between load and effort for any given lever is known as the Mechanical Advantage.
	Hydraulic pressure & force	Hydraulic pressure is transmitted through liquid & can transmit increased force.
	Bleeding	When you bleed a hydraulic system you are removing air from the system.

Electrics	Absolute zero	The theoretical temperature at which no further heat loss is possible, and at which all molecular movement would cease is called absolute zero.
	Atoms	Atoms are the building blocks of all matter. An atom is made up of protons, neutrons and electrons and bond together into stable groups of atoms called 'molecules'.
	Electrical charge	An electrical charge is a quantity of electrical energy that is held by an object such as a battery. Electric charge can be directly measured with an electrometer.
	Electrical conduction	Electrical conduction is the movement of electrically charged particles due to a force exerted by an electric field. The electric current formed by this movement travels through a conductor.
	Electrolyte	The acid solution in a vehicle battery is an electrolyte. An electrolyte is a substance that contains free ions and conducts electricity, usually a liquid.

Electronics	Subatomic particles	An atom is the basic component of a chemical element, but atoms themselves are composed of various combinations of smaller, or subatomic, particles, such as electrons, protons, and neutrons.
	Electronics	Electronics is the study and use of devices that operate by controlling the flow of electrons or other electrically charged particles.
	Faraday's law	Induction coils operate according to Faraday's law in order to step up the nominal battery voltage to the voltage needed to bridge the gap across the spark plug electrodes.
	Stepper motor	A stepper motor rotates in a series of very precise steps, controlled electronically by a microprocessor.
	Tolerance	Tolerance in engineering is an allowance made for imperfections in a manufactured object.
	Transformer	A transformer is an electrical device that transfers energy from one electrical circuit to another by magnetic coupling without moving parts.

Topic group	Topic	Summary