Energy, Radioactivity, Space Weather, and Space Exploration Vocabulary

Vocabulary flashcards defining core terms and formulas from physics and astronomy topics including energy, power, nuclear radioactivity, solar phenomena, and space exploration technologies.

Work

The product of force and displacement in the direction of force, given by $W = Fs$.

Energy

The ability to do work.

Power

The work done per unit time, given by $P = \frac{W}{t}$.

Gravitational Potential Energy

The work done to lift an object to a height from the Earth's surface, calculated as $GPE = mgh$.

Elastic Potential Energy

The work done to compress or stretch an elastic material over displacement of $x$ from an equilibrium position, given by $EPE = \frac{1}{2}Fx$.

Kinetic Energy

The energy possessed by a moving object, calculated using $KE = \frac{1}{2}mv^2$.

Principle of Conservation of Energy

The principle stating that energy cannot be created or destroyed, but can only be converted from one form to another.

Radioactivity

A random and spontaneous decay process of an unstable nucleus by emitting radioactive radiation such as alpha particles, beta particles, or gamma rays.

Radioactive Decay

A random and spontaneous process where an unstable nucleus emits radioactive radiation until the nucleus becomes more stable.

Curie (Ci)

A unit of radioactivity defined as $1\,\text{Ci} = 3.7 \times 10^{10}\,\text{decays/s}$.

Becquerel (Bq)

A unit of radioactivity defined as $1\,\text{Bq} = 1\,\text{decay/s}$.

Half-life of Radioactive Decay

The time taken for the number of undecayed nuclei to be reduced to half of its original number.

Positive Ion (Cation)

An atom that loses electrons, resulting in a positive net charge.

Negative Ion (Anion)

An atom that gains electrons, resulting in a negative net charge.

Ionising Radiation

Radiation that produces positive and negative ions while passing through air.

Non-ionising Radiation

Radiation that does not produce ions while passing through the air.

Cosmic Rays

High-energy radiation produced outside the Solar System.

Background Radiation

Ionising radiation released into the environment from various natural and man-made sources.

Granules

Grainy structures on the photosphere of the Sun that represent the upper part of the convection zone at temperatures around $\pm 5800\,^\circ\text{C}$.

Sunspot

Dark regions seen on the Sun's surface that have lower temperatures than their surroundings and serve as locations for very large eruptions.

Prominence

A huge loop of glowing gases over a sunspot that can reach heights of hundreds of thousands of kilometres.

Solar Flares

A column of large amounts of charged gases erupting from the Sun in a strong gas explosion.

Coronal Mass Ejections

A huge cloud of plasma that erupts from the Sun together with solar flares as an expanding cloud of magnetic gas.

Solar Wind

Particles such as electrons, protons, and alpha particles that erupt from the Sun into outer space.

Earth's Magnetosphere

The region in outer space surrounding the Earth where the Earth's magnetic field combines with the outer magnetic field.

Geocentric Model

A historical model of the Solar System constructed by Ptolemy with a stationary Earth at the centre and other celestial bodies revolving around it in circular orbits.

Heliocentric Model

A historical model of the Solar System constructed by Copernicus with the Sun at the centre and Earth rotating on its axis while revolving in circular orbits.

Space Probe

A spacecraft that carries cameras, remote sensing instruments, and communication tools to gather information and send it back to Earth as it travels into and out of the Solar System.

Remote Sensing

A method of gathering and recording information about an object or region from a distance.