1. 1
   A UK planetarium is designing a new exhibit for visitors explaining the layout of the Solar System, including the classification of objects that orbit the Sun.

   (a)

   How many planets are recognised in the Solar System, according to the exhibit's description?

   [1 mark]

   • A6
   • B7
   • C8
   • D9

   (b)

   Which of the following is classified as a dwarf planet rather than one of the eight planets?

   [1 mark]

   • AMars
   • BNeptune
   • CVenus
   • DPluto

   (c)

   Describe two ways in which a moon differs from a planet.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Historians of science describe how the Sun originally formed from a vast cloud of dust and gas billions of years ago, before the planets existed.

   (a)

   What is the name given to the cloud of dust and gas from which a star forms?

   [1 mark]

   • ANebula
   • BNucleus
   • CCorona
   • DPhotosphere

   (b)

   What force pulls the material of a nebula together to begin forming a protostar?

   [1 mark]

   • AMagnetic force
   • BGravitational force
   • CElectrostatic force
   • DNuclear force

   (c)

   Explain why a new star reaches a state of equilibrium during the early part of its life.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A satellite communications company operates several artificial satellites that orbit the Earth in circular paths to provide television signals to customers across the UK.

   (a)

   Explain what provides the force needed to keep an artificial satellite moving in a circular orbit around the Earth.

   [3 marks]

   (b)

   Describe two similarities and two differences between an artificial satellite and a natural satellite such as the Moon.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   (HT) Engineers monitoring a weather satellite note that, to remain in a stable circular orbit at a different height above the Earth, the satellite's speed must change accordingly.

   (a)

   Explain, in terms of gravity, why an object moving in a circular orbit has a constantly changing velocity but a constant speed.

   [6 marks]

   (b)

   Explain why a stable circular orbit at a smaller radius requires a greater orbital speed than a stable circular orbit at a larger radius.

   [6 marks]

   Total for question 4: 12 marks

End of questions