SQA National 5 Physics Area 2 Space: a complete overview of space exploration and cosmology

Area 2 Space sets the physics of motion and waves in a cosmic context. It has two key areas, space exploration and cosmology, and it reuses ideas from Dynamics (Newton's laws, weight, projectiles) and Waves (the electromagnetic spectrum). This guide maps both key areas and the relationships you need; each key area has its own answer page.

Space exploration

A rocket produces thrust by pushing hot exhaust gas backwards: by Newton's third law the gas pushes the rocket forwards with an equal and opposite force. Lift-off needs the thrust to exceed the weight, and the acceleration follows from $F = ma$ on the resultant. Weight changes from body to body because the gravitational field strength $g$ changes, $W = mg$, but mass is constant everywhere. A satellite is a projectile moving fast enough horizontally that it falls around the planet without landing, used for communication, weather, navigation and observation. Re-entry converts a craft's kinetic energy into heat through friction with the air, so a heat shield is needed.

Cosmology

Astronomers study the universe using the whole electromagnetic spectrum, with a different telescope for each band, because objects emit far more than visible light. Each element has a unique line spectrum, a fingerprint of wavelengths, so comparing a star's spectral lines with laboratory spectra reveals which elements it contains. The light from distant galaxies is redshifted (stretched to longer wavelengths) because they are moving away, with the redshift $z = (\lambda_{\text{observed}} - \lambda_{\text{rest}})/\lambda_{\text{rest}}$. Because more distant galaxies recede faster, this is the main evidence that the universe is expanding, the basis of the Big Bang model.

How Space is examined

Space questions mix short calculations (weight, resultant force and acceleration at lift-off, redshift) with explanation marks (Newton's third law for thrust, why mass is constant, how line spectra and redshift work). For calculations, show the relationship, substitution and answer with units. For explanations, use the correct named terms, especially "action and reaction force", "line spectrum" and "redshift", and link redshift clearly to galaxies moving away and the universe expanding.

For the official course specification

The SQA publishes the full National 5 Physics course specification, data sheet, relationships sheet and past papers at sqa.org.uk. Always revise from the current specification and SQA past papers.