National 5 Physics: Thermal Physics, Space Terms, and Astrophysics

Comprehensive vocabulary flashcards covering thermal physics (specific heat capacity and latent heat), orbital mechanics, space terminology, telescopes, spectroscopy, and cosmological theories from the National 5 Physics curriculum.

Specific Heat Capacity ($c$)

The heat energy required to raise the temperature of $1\,kg$ of a substance by $1\,^{\circ}C$. It is calculated using $E_H = cm\Delta T$, where values are unique to each material.

Specific Latent Heat ($L$)

The heat energy required to change the state of $1\,kg$ of a substance without any change in temperature ($E_H = mL$).

Specific Latent Heat of Fusion ($L_f$)

The heat energy required to change unit mass ($1\,kg$) of a substance from a solid to a liquid at its melting point without a temperature change.

Specific Latent Heat of Vaporisation ($L_v$)

The heat energy required to change unit mass ($1\,kg$) of a substance from a liquid to a gas at its boiling point without a temperature change.

Planet

An astronomical object that does not undergo nuclear fusion but orbits a star or sun.

Dwarf Planet

An object that orbits a star and is similar to a planet, but is not large enough to clear its orbital path of debris.

Moon

A natural satellite that orbits a planet.

Star

A large ball of hot gases undergoing nuclear fusion and emitting electromagnetic radiation.

Sun

A star located at the centre of a solar system.

Asteroid

An object that orbits the sun that does not fulfil planetary criteria.

Solar System

A central star orbited by planets.

Exoplanet

A planet located outside our solar system that orbits a star.

Galaxy

A cluster of gravitationally bound stars, gas, and dust clouds.

Universe

The entirety of cosmic structure consisting of many galaxies separated by empty space, with an estimated age of $13.8\text{ billion years}$.

Geostationary Satellite

A satellite that has an orbital period of $24\text{ hours}$ and orbits above Earth's equator at an altitude of $36\,000\,km$, remaining above the same point on Earth's surface.

Satellite Period

The time taken for a satellite to complete one full orbit around a planet; it increases as the height of the orbit increases.

Newton's Thought Experiment

A thought experiment showing that if an object is launched horizontally with sufficient velocity, the rate at which it falls towards Earth matches the rate at which the Earth curves away, placing the object into orbit.

Gravitational Slingshot (Gravity Assist / Catapult)

A manoeuvre where a spacecraft travels close to a planet, moon, or large asteroid to accelerate via gravitational attraction, gaining kinetic energy and speed while altering its trajectory.

Apparent Weightlessness in Orbit

The state experienced by astronauts because they are in free fall without a reaction force pushing up, despite the gravitational field strength at the ISS height still being approximately $8.7\,N\,kg^{-1}$.

Ion Drive

A propulsion mechanism that ionises Xenon gas and accelerates the positive ions between metal grids to eject them at high velocity, providing small, continuous thrust over an extended period according to Newton's third law.

Light Year

The distance that light travels through space in one year, calculated as $d = vt = (3 \times 10^8\,m/s) \times (365 \times 24 \times 60 \times 60\,s) \approx 9.5 \times 10^{15}\,m$ ($9.47 \times 10^{15}\,m$).

Stellar Spectroscopy

The study of the spectra of starlight used by astrophysicists to determine the physical and chemical properties of stars (such as temperature, age, size, and composition).

Continuous Spectrum

A spectrum that displays an unbroken sequence of all visible wavelengths and colours, emitted by hot, dense sources such as stars.

Line Emission Spectrum

A spectrum consisting of distinct, sharp bright lines at specific wavelengths produced by excited gas atoms, used to identify chemical elements present in astronomical objects.

Absorption Spectrum

A continuous spectrum with dark gaps or lines caused by cooler gases absorbing specific characteristic wavelengths of light passing through them.

The Big Bang Theory

The cosmological model stating that the universe originated from a rapid expansion from a very hot, dense single point of matter and continues to expand and cool.

Cosmic Microwave Background Radiation (CMBR)

Pervasive background radiation throughout space that serves as key observational evidence for the early expansion and cooling predicted by the Big Bang Theory.

Redshift

The shifting of galactic spectral lines towards longer wavelengths, showing that galaxies are moving away from each other and providing evidence that the universe is expanding.