Space PhysicsAQA GCSE Physics: Topic test

20 questions, 54 marks

AQA GCSE Physics

Space Physics topic test

Total 54 marks

Name

Class

Date

1
A planetary scientist studies a newly discovered dwarf planet in the outer solar system, orbiting the Sun in a stable, roughly circular path far beyond Neptune.
(a)
Which force provides the force that keeps the dwarf planet in its orbit around the Sun?
[1 mark]
AGravitational force
BMagnetic force
CElectrostatic force
DFriction force
(b)
Which of the following is the best description of our solar system?
[1 mark]
AA single galaxy containing billions of stars, of which the Sun is the largest
BOne star, eight planets, dwarf planets and natural satellites, forming a small part of the Milky Way galaxy
CEight stars orbiting a single planet
DThe Milky Way itself, containing only our Sun and its planets
(c)
(HT) The dwarf planet orbits the Sun in a stable circular orbit. Explain why, even though its speed stays constant, its velocity does not, and why this means a resultant force must be acting on it.
[2 marks]
Total for question 1: 4 marks
2
An astronomy textbook describes the life cycle of a star similar in size to our Sun, from the initial cloud of dust and gas through to its final, cold remnant.
(a)
Which stage comes immediately after the main sequence stage in the life cycle of a star similar in size to the Sun?
[1 mark]
ASupernova
BNeutron star
CRed giant
DProtostar
(b)
What happens during a star's protostar stage that allows it to become a stable main sequence star?
[1 mark]
AThe star cools completely and stops emitting light
BAll fusion reactions permanently stop
CThe star begins orbiting a planet
DAn equilibrium is reached between gravitational collapse and the expansion caused by fusion energy released in the core
(c)
State the correct order of the remaining stages in the life cycle of a star similar in size to the Sun, after it leaves the red giant stage.
[2 marks]
Total for question 2: 4 marks
3
An astronomer compares the light spectrum from a distant galaxy with the spectrum of light produced by the same chemical elements in a laboratory on Earth. She finds that specific dark lines in the galaxy's spectrum, caused by those elements, appear at longer wavelengths than the same lines measured in the laboratory.
(a)
State the name given to this shift to longer wavelengths, and explain what it indicates about the motion of the distant galaxy relative to the Earth.
[3 marks]
(b)
Explain how observations of red-shift from many distant galaxies provide evidence that the universe is expanding, and how this evidence supports the Big Bang theory.
[4 marks]
Total for question 3: 7 marks
4
A science communicator explains to the public how elements such as gold and iron, found in jewellery and everyday objects, were originally created inside stars much more massive than the Sun.
(a)
Describe the life cycle of a star much more massive than the Sun, from nebula to its eventual fate, and explain how fusion processes inside such a star produce elements up to iron.
[6 marks]
(b)
Explain how elements heavier than iron, such as gold, are produced, and how these elements come to be found throughout the universe, including on Earth.
[6 marks]
Total for question 4: 12 marks
5
A telecommunications company launches a new artificial satellite into a stable circular orbit around the Earth, at a fixed height above the equator, to provide internet coverage to a region.
(a)
What must be true for the satellite to remain in a stable circular orbit at a constant height?
[1 mark]
AThe gravitational force must provide exactly the force needed to keep it moving in a circle at that speed and radius
BThe satellite's engines must fire continuously to keep it moving
CThere must be no gravitational force acting on the satellite
DThe satellite's mass must be zero
(b)
(HT) If the satellite were moved to a stable orbit at a smaller radius (closer to the Earth), what would happen to its orbital speed?
[1 mark]
AIt would decrease
BIt would increase
CIt would stay exactly the same
DThe satellite could not orbit at all at a smaller radius
(c)
(HT) Explain why, for a satellite in a stable circular orbit, its speed stays constant even though gravity is constantly acting on it, and explain why this means the orbital speed must change if the radius changes.
[2 marks]
Total for question 5: 4 marks
6
An amateur astronomer observes that the Sun has remained roughly the same size and brightness for billions of years, despite constantly undergoing fusion reactions in its core.
(a)
Which of these describes the equilibrium that keeps a main sequence star like the Sun a stable size?
[1 mark]
AThe star is not affected by gravity at all
BFusion reactions have completely stopped in the Sun
CGravitational collapse is balanced by the outward expansion caused by energy released in fusion reactions
DThe Sun's mass is decreasing so quickly that it is shrinking rapidly
(b)
What will eventually happen to the Sun once the hydrogen fuel in its core begins to run low?
[1 mark]
AIt will remain a main sequence star forever
BIt will immediately become a black hole
CIt will explode as a supernova
DIt will expand to become a red giant
(c)
Explain why the Sun is expected to become a red giant, rather than undergo a supernova explosion, at the end of its main sequence stage.
[2 marks]
Total for question 6: 4 marks
7
Since 1998, astronomers analysing the brightness of distant supernovae have found evidence that the rate at which the universe is expanding is not constant, but is increasing over time.
(a)
Explain what is meant by the Big Bang theory, and state one piece of observational evidence that supports it.
[3 marks]
(b)
Explain what the discovery that the universe's rate of expansion is increasing suggests about our current scientific understanding of the universe, and name one related concept that scientists still do not fully understand.
[4 marks]
Total for question 7: 7 marks
8
A university physics department is giving an open lecture. The lecturer explains that, although red-shift evidence strongly supports the Big Bang theory, physicists still do not fully understand what makes up most of the universe's mass and energy, and that every atom of iron in a student's blood was created inside a star that died long ago.
(a)
Explain, step by step, how red-shift observations of distant galaxies led scientists to develop the Big Bang theory of the origin of the universe, and explain why supernova observations since 1998 have added a further, more advanced idea to this theory.
[6 marks]
(b)
Explain what the lecturer means by saying that 'every atom of iron in a student's blood was created inside a star that died long ago', linking the life cycle of massive stars to the composition of the Earth and living things. Evaluate why scientists say there is 'still much about the universe that is not understood', giving two examples.
[6 marks]
Total for question 8: 12 marks

End of questions