Fukuoka Entrance Science key terms

A push or pull that acts on an object and can change its speed, its direction, or its shape. It is measured in newtons and always has both a size and a direction.

The rule that whenever one object pushes or pulls another, the second object pushes or pulls back with an equal force in the opposite direction. Forces therefore always come in matched pairs.

The rate at which velocity changes, either because the speed changes or because the direction changes. It is calculated by dividing the change in velocity by the time taken and is measured in metres per second squared.

Speed in a stated direction. Two cars travelling at the same speed but in opposite directions have different velocities, even though their speeds are identical.

The energy an object possesses because it is moving. It grows with the mass of the object and increases with the square of its speed, so doubling the speed gives four times the energy.

Stored energy that an object has because of its position or condition, such as a raised ball or a stretched spring. It can be converted into other forms when the object moves or changes.

The principle that energy cannot be created or destroyed, only transferred between objects or changed from one form into another. The total amount stays the same, although some may spread as heat.

The relationship stating that the current through a conductor equals the voltage across it divided by its resistance. It links the three quantities in a simple circuit and is written as I equals V divided by R.

The flow of electric charge through a conductor, measured in amperes. It flows only when a complete circuit is formed and is driven by a source of voltage such as a battery.

A measure of how strongly a component opposes the flow of electric current, measured in ohms. Thinner, longer wires and certain materials have higher resistance, which reduces current for a given voltage.

A magnet produced by winding a coil of wire around an iron core and passing a current through the wire. Its magnetism can be switched on and off, and its strength increases with current and number of turns.

The number of complete waves or vibrations passing a point each second, measured in hertz. A higher frequency means a higher-pitched sound or, for light, a colour nearer the violet end of the spectrum.

The distance between two matching points on consecutive waves, such as from one crest to the next. It is usually measured in metres and is closely related to frequency and wave speed.

The maximum distance a wave or vibrating particle moves from its rest position. A larger amplitude carries more energy and, for sound, is heard as a louder volume.

The bending of light or another wave as it passes from one material into another at an angle, caused by a change in wave speed. It explains why a straw looks bent in a glass of water.

The bouncing back of light or another wave when it strikes a surface. The angle at which the wave arrives equals the angle at which it leaves, both measured from the normal to the surface.

A shaped piece of transparent material that bends light to form an image. A convex lens converges light and can magnify, while a concave lens spreads light outwards.

Two or more substances combined without chemically joining, so each keeps its own properties. Mixtures can usually be separated by physical methods such as filtering, sieving, or distillation.

Material made of only one kind of element or compound, with a fixed composition. Unlike a mixture, it has a sharp melting point and cannot be separated by simple physical means.

A substance formed when atoms of two or more different elements are chemically joined in fixed proportions. Its properties differ from those of the elements it contains, and it can only be split by chemical reactions.

The smallest particle of a substance that still has the properties of that substance, made of two or more atoms bonded together. Water, for example, exists as molecules of two hydrogen atoms joined to one oxygen atom.

The smallest unit of an element that can take part in a chemical reaction. It has a tiny central nucleus containing protons and neutrons, surrounded by electrons.

An atom or group of atoms that has gained or lost electrons, giving it a positive or negative charge. Ions allow solutions to conduct electricity and are released when acids dissolve in water.

A written statement using symbols and formulas to show the reactants and products of a reaction. It must be balanced so that the number of atoms of each element is the same on both sides.

A scale from 0 to 14 describing how acidic or alkaline a solution is. Values below 7 are acidic, 7 is neutral, and above 7 is alkaline; each step represents a tenfold change in acidity.

The reaction between an acid and a base that produces a salt and water, bringing the pH closer to neutral. It is used to treat acidic soil and to relieve indigestion.

A solid that forms and separates out of a solution during a chemical reaction. Its appearance, such as a white cloudiness or coloured particles, is often evidence that a reaction has occurred.

A separation method that passes a mixture through a filter material, trapping solid particles while the liquid passes through. It separates an insoluble solid from a liquid, as in purifying drinking water.

The thin, flexible outer layer of a cell that controls what enters and leaves. It encloses the cell contents and allows useful substances in while keeping harmful ones out.

A stiff outer layer surrounding the membrane of plant cells, made mainly of cellulose. It gives the cell shape and support and is absent from animal cells.

A green structure found in plant cells that contains chlorophyll and carries out photosynthesis. It captures light energy and uses it to make sugars from carbon dioxide and water.

The process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen. It takes place mainly in leaves and provides the food base for most ecosystems.

The chemical process in living cells that releases energy from glucose, using oxygen and producing carbon dioxide and water. It happens continuously in plants and animals, day and night.

A type of cell division that produces reproductive cells with half the normal number of chromosomes. It creates genetic variety because chromosomes are shuffled and recombined.

Cell division that produces two offspring cells genetically identical to the parent cell. It is used for growth and for replacing worn-out cells in the body.

A thread-like structure in the nucleus that carries genes made of DNA. Humans have 46 chromosomes in most body cells, arranged in 23 pairs.

A section of DNA that carries the instructions for a particular characteristic or protein. Genes are passed from parents to offspring and exist in different versions called alleles.

A characteristic that appears in an organism whenever at least one copy of its gene is present. The alternative, recessive trait shows only when both copies are recessive.

An organism that makes its own food using sunlight, usually through photosynthesis. Plants and algae are producers and form the first level of every food chain.

An organism that obtains energy by eating other organisms rather than making its own food. Herbivores, carnivores, and omnivores are all consumers and occupy higher levels of a food chain.

A diagram showing the many interconnected feeding relationships among organisms in an ecosystem. It illustrates how energy flows from producers to various consumers and decomposers.

The theory that Earth's rigid outer shell is broken into large plates that move slowly over the softer layer beneath. Their collisions and separations cause earthquakes, volcanoes, and mountain building.

A sudden shaking of the ground caused by the release of built-up stress along a fault in Earth's crust. The point of origin underground is the focus, and the point above it is the epicentre.

An opening in Earth's surface through which molten rock, ash, and gases escape from below. Most volcanoes occur near plate boundaries where magma can rise to the surface.

The boundary where two air masses of different temperature and humidity meet. Passing fronts bring characteristic changes such as rain, shifting winds, and a rise or fall in temperature.

A large body of air with fairly uniform temperature and moisture throughout. Its properties depend on the region where it formed, such as over a warm ocean or a cold landmass.

The Sun together with all the objects bound to it by gravity, including eight planets, dwarf planets, moons, asteroids, and comets. Planets orbit the Sun in nearly circular paths.

The curved path an object follows as it moves around a larger body under the influence of gravity. Earth orbits the Sun once a year, while the Moon orbits Earth about once a month.

A huge sphere of hot gas that produces its own light and heat through nuclear reactions in its core. The Sun is the nearest star to Earth, and stars differ greatly in size and temperature.

An enormous grouping of billions of stars, gas, and dust held together by gravity. Our Sun belongs to the Milky Way, one of countless galaxies in the universe.