AQA GCSE Physics 34 Stars

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AQA GCSE Physics 3-4Stars Space

• GCSE Physics pages 266 to 275

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AQA GCSE Specification

• STARS GALAXIES
• 13.10 What is the life history of stars?
• Using skills, knowledge and understanding of how
  science works
• to explain how stars are able to maintain
  their energy output for millions of years
• to explain why the early Universe contained
  only hydrogen but now contains a large variety of
  different elements.
• Skills, knowledge and understanding of how
  science works set in the context of
• Our Sun is one of the many millions of stars
  in the Milky Way galaxy.
• The Universe is made up of at least a billion
  galaxies.
• Stars form when enough dust and gas from space
  is pulled together by gravitational attraction.
  Smaller masses may also form and be attracted by
  a larger mass to become planets.
• Gravitational forces balance radiation
  pressure to make a star stable.
• A star goes through a life cycle (limited to
  the life cycle of stars of similar size to the
  Sun and stars much larger than the Sun).
• Fusion processes in stars produce all
  naturally occurring elements. These elements may
  be distributed throughout the Universe by the
• explosion of a star (supernova) at the end of its
  life.

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GalaxiesNotes questions from pages 266 267

• (a) What is a galaxy? (b) Name our galaxy. (c)
  How many galaxies are there?
• Copy and answer question (a) on page 266.
• Outline the history of the Universe to the
  present day.
• Explain the part played by gravity in the
  evolution of the Universe.
• Copy and answer questions (b) and (c) on page
  267.
• Copy the Key points table on page 267.
• Answer the summary questions on page 267.

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Galaxies ANSWERS

• In text questions
• When we use a powerful telescope to see a distant
  galaxy, we are seeing the galaxy as it was
  billions of years ago because the light from it
  has taken billions of years to reach us.
• About 13 billion years.
• They are both positively charged, so they repel
  each other. The force of repilsion is much
  greater than the force of gravity between them.

• Summary questions
• 1. (a) Expanded, cooled.
• (b) Attracted.
• (c) Formed.
• 2. (a) (i) We could not send a probe far enough.
• (ii) Galaxies take millions of years to form we
  couldnt wait that long.
• (b) (i) Gravitational forces hold the stars
  together.
• (ii) The Universe has expanded leaving these
  vast spaces.

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The life history of a star Notes questions from
pages 268 269

• Copy Figure 2 on page 269.
• Outline the life history of a star like our Sun.
  Your account should include what is meant by (a)
  protostar, (b) red-giant, and (c) white dwarf.
• Explain the additional stages undergone by the
  most massive stars. Your account should include
  what is meant by (a) supernova, (b) neutron star,
  and (c) black hole.
• (a) How does a star produce energy? (b) Explain
  why the Sun is neither expanding or contracting
  at the present time.
• Copy and answer questions (a), (b), (c) and (d)
  on pages 268 and 269.
• Copy the Key points table on page 269.
• Answer the summary questions on page 269.

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The life history of a star ANSWERS

• In text questions
• The potential energy of gas and dust decreases
  when it gathers and is transformed into heat
  energy.
• The outward pressure of radiation from its core
  stops it collapsing.
• Gravity.
• Gravity.

• Summary questions
• 1. (a) B, A, C, D.
• (b) (i) A
• (ii) It will fade out and go cold.
• 2. (a) (i) Expand, collapse.
• (i) Explode, collapse.
• (b) (i) The neutron star must have sufficient
  mass.
• (ii) The gravitational field is so strong that
  nothing can escape from it.

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How the chemical elements formed Notes
questions from pages 270 271

• Explain the two different processes by which (a)
  lighter and (b) heavier elements were formed.
• Copy and answer questions (a) and (b) on pages
  270 and 271.
• Outline the ways of trying to discover the
  presence of extra-terrestial life.
• Copy and answer question (c) on page 271.
• Copy the Key points table on page 271.
• Answer the summary questions on page 271.

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How the chemical elements formed ANSWERS

• In text questions
• In a supernova explosion.
• Its half-life is very short compared with the age
  of the Sun. Any plutonium formed when the Sun
  formed would have decayed long ago.
• Carbon atoms are in all the molecules that make
  up living objects.

• Summary questions
• (a) Hydrogen.
• (b) Uranium.
• (c) Helium, iron.
• (d) Hydrogen.
• 2. (a) Stars, supernova.
• (b) Supernova, galaxy.
• (c) Stars, supernova.

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Universal issues Notes questions from pages 272
273

• Answer questions (a), (b) and (c) on page 272.

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Universal issues ANSWERS

• 2 km
• 9000 km
• over 30 million km

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How Science Works ANSWERS

• Myths how the Earth was created by Phan Ku.
• Observations that the Sun, moon, planets and
  stars move across the sky.
• The data concerning the size of the Moon.
  Ptolomys Earth-centred model required the Moon
  to speed up and slow down and hence therefore to
  change its size as seen from Earth. The Moon,
  when measured, did not show these changes in
  apparent size.
• Example of hypothesis Anaxagoras hypothesised
  that the Sun and the Moon were made of rocks.

• Ptolomys Earth-centred theory of the Universe.
• Copernicus theory of the universe because it is
  supported by much evidence, but theories are not
  completely proven in all instances and therefore
  always open to being disproved. This is more
  obviously shown by Bruno. Planets are being
  discovered around stars, but there is no evidence
  of life outside of the Earth.
• Anaxagoras and Bruno were examples of political
  influences on science.