Space

• What type of force pulled together the cloud of dust and gas to form the sun?

  Gravitational force of attraction
• What is a cloud of dust and gas?

  A nebula
• What type of reactions take places at the start of a star’s life cycle as dust and gas is drawn together?

  Fusion reactions
• Which two phases do all stars if the same or greater size than the sun undergo?

  Protostar phase

  Main sequence phase
• What do all stars of a similar magnitude to the sun become at the end of their life cycle?

  A black dwarf
• What two things can stars much bigger than the sun become at the end of their life cycle?

  Neutron star

  Black hole
• What two phases do stars of a similar size to the sun go through between being a main sequence star and a black dwarf?

  1: Red giant

  2: White dwarf
• What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole?

  1: Red super giang

  2: Supernova
• What are produced during the fusion processes in a star?

  All of the naturally occurring elements
• How are elements heavier than iron produced?

  In a supernova
• What type of nuclei fuse together to form heavier elements in a star?

  Hydrogen nuclei
• How are elements distributed throughout the universe?

  Through the explosion of a massive star (supernova)
• What allows planets and satellites to maintain circular orbits?

  > Gravity provides the gravitational force that acts as the object’s centripetal force

  > The presence of a centripetal force allows this
• Explain why for a stable orbit, the radius of orbit must change if the speed changes?

  > At higher speeds, the object requires a greater centripetal force

  > For a greater centripetal force, the gravitational force must increase

  > This is achieved by the radius of the orbit being reduced
• Explain how the force of gravity acting on a satellite affects its speed and velocity:

  > The force can alter its velocity since the direction is continually changing

  > It can’t cause a change of speed since there is no force component in the direction of motion
• What is red shift?

  An observed increase in the wavelength of light from distant galaxies
• What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?

  > The further away a galaxy is, the faster it is moving

  > The further away a galaxy is, the greater the observed increase in wavelength
• What does red shift provide evidence for?

  > Provides evidence that the universe is expanding

  > Supports the Big Bang theory
• Compare the observed red shift if two galaxies, one further away than the other:

  > The galaxy that is further away is travelling faster

  > The observed red shift is greater the further away it is
• What do Supernovae suggest about the expansion of the universe?

  Suggested that galaxies are moving away at an ever faster rate
• Prior to observations of supernovae, what was believed about the universe?

  > The rate of expansion was expected to occur at an ever slower rare

  > It was thought that gravitational forces would cause this slowing down