Space objects
This glowing ball of gas travels around a galaxy and produces energy through fusion.
A star
A skydiver reaches terminal velocity because two forces become equal. Name them.
weight (gravity) and air resistance
This element is the main fuel for nuclear fusion in stars.
Hydrogen
Mass = 12 kg, g = 9.8 N/kg. Calculate weight.
117.6 N
Explain why the Moon always shows the same face to Earth.
It is tidally locked — its rotation period equals its orbit period.
This is a small rocky object that orbits the Sun, mostly found between Mars and Jupiter.
What is an asteroid?
Why does the temperature in a protostar increase as gravity pulls material inward?
Because particles move faster and collide more often as they are compressed, increasing thermal energy.
When hydrogen fuses in the Sun, it forms this element.
Hellium
A car accelerates from 5 m/s to 25 m/s in 4 seconds. Calculate its acceleration.
5 m/s²
Why doesn’t a black hole “suck in” everything around it like a vacuum cleaner?
Objects still orbit normally unless they cross the event horizon.
You spot a super-dense object left behind after a supernova. It’s not massive enough to be a black hole, but it spins rapidly and sends beams of radiation like a lighthouse.
A neutron star (or pulsar).
As a protostar forms, gravity pulls particles inward. What force increases inside the core to oppose gravity?
Pressure from heating/compression.
What two conditions inside a star control its fusion rate?
Temperature and pressure (or density).
A spacecraft travels 1.2 × 10⁹ m in 2.0 × 10³ s. Calculate its average speed
6.0 × 10⁵ m/s
Why do red giants become much larger even though their cores shrink?
Gravity compresses the core → outer layers heat up → expand.
This dwarf planet is found in the Kuiper Belt
Pluto
This law explains why astronauts feel “weightless” in orbit.
Newton’s 1st Law
Why does fusion stop in a low-mass star after helium is produced?
It cannot reach the temperature needed to fuse heavier elements.
Convert 4500 nm to micrometres (µm).
(1 µm = 1000 nm)
4500÷1000=4.5
4.5 µm
State one reason the Sun will not become a black hole.
It does not have enough mass to collapse into one.
"This is the name of the rover that landed on Mars in 2021 to study the planet’s geology and search for signs of past life."
Perseverance
Explain what happens when gravity becomes stronger than the outward pressure inside a forming star.
The core continues to collapse and heats up further until it reaches the temperature needed for nuclear fusion.
Explain why iron cannot release energy through fusion in a star’s core.
Fusion of iron requires energy instead of releasing it, so fusion stops at iron.
A cell is 2.4 × 10⁻⁵ m long.
Convert this length to micrometres (µm) using standard form.
Answer: 24 µm
Explain why astronauts must exercise in space to prevent bone and muscle loss.
Microgravity reduces mechanical loading → bones lose calcium → muscles weaken unless regularly used.