AQA GCSE Physics Physics Paper 2 (Foundation), June 2025: Question 3

✅ Correct Answers

• A natural satellite of a planet is called a moon. [1 mark]
• A planet orbits a star. [1 mark]

💡 Key Knowledge

• Natural satellites: Moons orbit planets due to gravity. (Artificial satellites are man-made).
• Planetary orbits: Planets are large bodies orbiting a central star (the Sun in our solar system).

🧠 Exam Technique

Always check the mark scheme condition: "this order only". Putting "star" first and "moon" second scores 0 marks.

❌ Common Errors

Confusing nebula or galaxy with orbital parents. A planet does not directly orbit a nebula or a whole universe.

✅ Correct Answer

Milky Way [1 mark]

💡 Key Knowledge

Our solar system is part of the Milky Way galaxy, a barred spiral galaxy containing hundreds of billions of stars.

❌ Common Errors

Ticking Andromeda. Andromeda is our nearest major spiral neighbouring galaxy, but it is not our own.

✅ Correct Answer

It will become a black dwarf. [1 mark]

💡 Key Knowledge: Life Cycle of a Medium Star

Nebula → Protostar → Main sequence star (Sun) → Red giant → White dwarf → Black dwarf.

Only stars with a mass much greater than the Sun end as a neutron star or black hole (via a supernova).

🧠 Exam Technique

Look at the mass of the star! The question specifies "the Sun". The Sun does not have enough mass to undergo a supernova explosion.

❌ Common Errors

Selecting black hole because it sounds dramatic. Stars the size of the Sun never form black holes.

✅ Correct Answer

A very distant galaxy moves faster. [1 mark]

💡 Key Knowledge: Hubble's Law

The further away a galaxy is from Earth, the faster it is moving away from us (recession velocity is directly proportional to distance).

❌ Common Errors

Assuming all galaxies move away at the same speed, or that more distant ones move slower because they are further away.

✅ Correct Answer

Red-shift [1 mark]

💡 Key Knowledge: Doppler Shift in Light

• Red-shift: Light waves are stretched (wavelength increases) as the source moves away from the observer. Red is at the long-wavelength end of visible light.
• Blue-shift: Wavelength decreases (compressed) when an object moves towards us.

🧠 Memory Aid

Red = Receding (longer wavelength). If distant galaxies are moving away, their light is red-shifted.

✅ Correct Answer

The Big Bang theory suggests that the universe began from a region that was extremely hot. [1 mark]

💡 Key Knowledge

According to the Big Bang theory, the universe began from an extremely small, dense, and hot region.

❌ Common Errors

Choosing cold (confusing initial hot Big Bang with the cold expanse of deep space today) or large (it began at a point of near-zero volume).

✅ Correct Answer

The universe is getting bigger. [1 mark]

💡 Key Knowledge

Because distant galaxies show red-shift in all directions, space itself is continuously stretching and expanding — meaning the universe is continually getting bigger.

❌ Common Errors

Selecting "the size of the universe is constant". This was the historical steady-state view, which was disproved by red-shift observations.