The supports for rotating mechanical parts such as axles and wheels. They should have as little friction as possible so the axles or wheels can turn easily.
Bracing structures
A brace is a support used to steady, strengthen or stiffen a structure. Many buildings, bridges and other constructions have bracing structures.
Architectural structures, usually made of stone or brick, built against walls to add strength or support.
A device that converts a circular motion into a linear motion. It is usually fixed on a shaft or axle. As the shaft turns, the cam pushes against an object (a cam follower) to make it move back and forth in a straight line. For example:
  • the up and down motion of the ‘stamper’ in a stamping battery
  • the up and down motion in the seesaw, or the side to side ‘wobbling’ of the duck featured in the pull-along toy project.
Diagram of a cam in a toyDiagram of a cam in a stamping battery
Cam Follower
A lever or other machine part which moves back and forth in contact with a cam rotating on a shaft or axle.
Diagram of a cam follower
A pushing force that flattens or shortens the thing upon which it is acting.
The reverse of evaporation – that is, when a gas or vapour becomes a liquid, usually by cooling.
Areas of relatively high ground separating basins through which streams and rivers flow.
The force or energy applied to a machine to get it to work.
Elastic potential energy
Potential energy stored as a result of the compression or stretching of an elastic object, such as the stretching of a spring. This stored up energy can be released and turned into kinetic energy.
Electromagnetic spectrum
The total range of wavelengths of electromagnetic radiation. Visible light is a small part of the electromagnetic spectrum. It also includes x-rays and ultra violet rays (high frequency) and infra-red and radio waves (low frequency).
The process of turning a liquid into a gas or vapour. This happens more quickly if the liquid is heated.
An inclined, narrow, artificial channel constructed to provide water for water wheels, power generation etc.
Any influence that can produce a change in the speed, direction or shape of an object.
Fossil fuels
Fuel made from the compressed remains of ancient animals and plants. It includes coal, gasoline, natural gas and diesel fuel. These fuels are non-renewable forms of energy (i.e. once they are used they can never be replaced).
The resistance between two surfaces as they move against each other. For example, the friction between the soles of your shoes and the floor is what prevents you from slipping and falling down.
Areas of land that slope downwards.
Gravitational potential energy
The energy an object possesses because of its position in a gravitational field. Think about riding a bike up a hill. As you ride, the work you are doing is storing up gravitational potential energy. You can turn this back into kinetic energy by free-wheeling back down the hill.
The force of attraction between two objects. Because the Earth has a big mass, it attracts objects to it. This is what makes objects ‘fall’ downwards.
Greenhouse effect
The warming of the Earth’s surface by solar radiation trapped by a build-up of carbon dioxide and other atmospheric gases.
Water that collects or flows beneath the Earth’s surface.
Head race
A channel that carries water to a water wheel.
The various tributaries of a stream or river in the area in which it rises (begins to flow).
Kinetic energy
The energy of objects that are moving. For example, a wind-up toy that has been wound has potential energy which transforms to kinetic energy when it is released.
Kinetic friction
The force of friction between two surfaces that are moving relative to each other. For example, think about sliding down a water slide. There is kinetic friction between the slide and the person.
A weight that needs to be lifted, moved or supported.
Mechanical advantage
The advantage you gain when you use a machine to help you increase the force you can transmit. It can be calculated by dividing the resistance force (the force applied by a machine) by the effort force (the force applied to the machine).
Mill pond
A pool formed by damming a stream to provide water to turn a millwheel.
Mill race
The current of water that runs along a channel to turn a water wheel.
Parabolic path
A curve traced by objects when fired or thrown into the air then falling to Earth.
Parabolic reflectors
Concave (inwardly curved) reflective devices used to collect or distribute energy such as heat or light.
Parallel circuit
This is when the circuit divides to make two or more pathways for the current to flow.
Diagram of a parallel circuit
The process of heating a food (usually liquids) and cooling it immediately to slow the growth of microbes.
Potential energy
Potential energy is stored energy. For example, when you hold down a spring it contains potential energy before you release it.
Water or ice that falls from a cloud in the form of rain, drizzle, snow, sleet, or hail.
Rotary motion
When an object moves in a circular motion centred around a specific point (an axis).
Series circuit
This is when components in a circuit are arranged one after the other in the same circuit.
Diagram of a series circuit
The ‘overflow’ structure of a dam or reservoir that allows the excess water to flow downstream.
Static friction
The force of friction between two touching surfaces that are not moving relative to each other. The friction that occurs between a book and a desktop is an example of static friction. Another force, greater than the friction between the book and the desk, must be applied for the book to slide across the desk.
A process that eliminates or kills life forms such as bacteria and viruses. It is usually done by heat, chemicals, radiation or high pressure.
Tail race
A channel that carries water away from a water wheel.
A pulling force that tends to expand or lengthen the thing upon which it is acting.
The land forms and surface features of an area.
The process by which water absorbed by a plant is evaporated into the atmosphere from the plant’s leaves.
Streams, rivers or glaciers that feed into other larger streams or rivers.
A measure of the cloudiness of water due to suspended particles, that are usually invisible to the naked eye. The more turbid the water, the harder it is to see through.
Turning effect
This is the effect of a force in turning a lever or a wheel. For example, think about the ‘turning effect’ of a person on a seesaw. The ‘turning effect’ will depend on the person’s weight (the heavier the person, the more the turning effect), and where they are sitting (the further from the balance point in the middle, the more turning effect).
The highest point of (or the point opposite the base of) a figure.
Long bridges (for carrying a road or railway across a valley etc.) made up of sets of arches supported by rows of piers or towers.
Water flume
A water flume (head race) delivers water to a water wheel.
Dividing landforms, such as ridges, between two river systems. Can also be water basins draining to a defined point.
The distance between the peak and trough of one cycle of a wave of heat, light, or other energy.
Diagram of a wave showing wavelength