Fukushima Entrance Science key terms

The rate at which velocity changes with time, including changes in speed, direction, or both. It is measured in metres per second squared and is caused by a net force.

The rule that the net force on an object equals its mass multiplied by its acceleration. A larger force produces greater acceleration, while a larger mass resists it.

The product of an object's mass and its velocity, describing how hard it is to stop. In a closed system the total momentum stays constant during collisions.

The energy an object possesses because it is moving, calculated as one half of mass times velocity squared. It increases rapidly with speed and can be transferred in collisions.

Stored energy an object has because of its position or condition, such as height in a gravitational field or compression of a spring. It can convert into kinetic energy.

The principle that energy cannot be created or destroyed, only transferred or transformed between forms. The total energy of an isolated system remains constant over time.

The relationship stating that current through a conductor equals voltage divided by resistance, when temperature is constant. It links the three central quantities of simple circuits.

The rate at which electric charge flows past a point in a circuit, measured in amperes. It requires a closed path and a source of electromotive force.

The generation of an electromotive force in a conductor when it experiences a changing magnetic field. This principle underlies electric generators and transformers.

A disturbance that transfers energy through space or a medium without permanently moving matter. Waves are described by wavelength, frequency, and amplitude.

The number of complete wave cycles passing a fixed point each second, measured in hertz. Higher frequency means shorter wavelength for a wave travelling at fixed speed.

The bending of a wave as it passes from one medium into another where its speed differs. The change in direction results from a change in wave speed.

The time required for half of the radioactive nuclei in a sample to decay. After each half-life the remaining amount is halved, so activity falls exponentially.

The spontaneous emission of particles or radiation from an unstable atomic nucleus as it changes to a more stable state. The process is random for individual atoms.

One of two or more forms of the same element whose atoms have equal protons but different numbers of neutrons. Isotopes share chemistry but may differ in nuclear stability.

The number of protons in the nucleus of an atom, which determines the element's identity and its position in the periodic table. It is written as Z.

An arrangement of elements in order of increasing atomic number, grouped by recurring chemical properties. Elements in the same column share similar outer electron configurations.

The attraction holding atoms together in compounds, formed by sharing or transferring electrons. Bond type strongly influences a substance's melting point and conductivity.

A scale from 0 to 14 expressing the acidity or alkalinity of an aqueous solution based on hydrogen ion concentration. Values below 7 are acidic and above 7 are basic.

The reaction between an acid and a base that produces a salt and water, bringing the pH toward 7. The reaction releases heat and consumes both reactants.

The amount of substance containing as many elementary particles as there are atoms in 12 grams of carbon-12, about 6.02 times ten to the twenty-third. It links mass and particle number.

A chemical change in which a substance loses electrons, often by gaining oxygen or losing hydrogen. It is always accompanied by reduction of another substance.

A thin, flexible barrier surrounding every cell, made of a phospholipid bilayer with embedded proteins. It controls which substances enter and leave the cell.

The net movement of particles from a region of higher concentration to one of lower concentration, driven by random motion. It requires no energy input from the cell.

The diffusion of water across a partially permeable membrane from a dilute solution to a more concentrated one. It is a passive process important for cell water balance.

A protein that speeds up a specific biochemical reaction by lowering its activation energy. Its activity depends on temperature and pH and it is not consumed.

The process by which plants and other organisms use light energy to convert carbon dioxide and water into glucose and oxygen. It occurs mainly in chloroplasts.

The release of energy from glucose inside cells, either with oxygen or without it. Aerobic respiration produces carbon dioxide and water as waste products.

A type of cell division producing two genetically identical daughter cells, used for growth and repair. Chromosomes are copied and then separated equally.

A reduction division producing four daughter cells, each with half the chromosome number of the parent. It creates genetic variation through gamete formation.

A section of DNA that carries the instructions for making a particular protein or trait. Genes are passed from parents to offspring during reproduction.

The theory that Earth's rigid outer shell is broken into plates that move over the mantle. Their interactions cause earthquakes, volcanoes, and mountain building.

A sudden release of stored elastic energy in Earth's crust, producing ground shaking. It occurs mainly where tectonic plates slip past or collide with one another.

An elastic wave generated by an earthquake or explosion and travelling through Earth. Different wave types travel at different speeds and reveal Earth's interior.

The breakdown of rocks and minerals in place by physical, chemical, or biological processes. Unlike erosion, it does not involve transport of the material.

The transport of weathered rock and soil by moving water, wind, or ice. It shapes landscapes and carries sediment to new deposition sites.

Rock formed when layers of sediment are compacted and cemented over long periods. Its strata often preserve fossils and record past environments.

The warming of a planet's surface as certain atmospheric gases absorb and re-emit outgoing infrared radiation. Without it, Earth would be far colder than it is.

The fraction of incoming solar radiation reflected by a surface, expressed from 0 to 1. Ice and snow have high albedo, while oceans have low albedo.

The Sun and all bodies gravitationally bound to it, including planets, moons, asteroids, and comets. Its structure reflects conditions during its formation from a nebula.

The attractive force between any two masses, increasing with mass and decreasing with distance. It governs orbits, tides, and the falling of objects on Earth.