1. 1
   A geography teacher explains to a class why different parts of the world experience day and night at different times, and why the Sun appears to rise in the east and set in the west.

   (a)

   What is the correct explanation for this daily cycle?

   [1 mark]

   • AThe Earth rotates on its own axis approximately once every 24 hours
   • BThe Sun orbits the Earth once every 24 hours
   • CThe Earth orbits the Sun once every 24 hours
   • DThe Moon blocks sunlight from reaching half the Earth at any time

   (b)

   The teacher also explains that the Earth's axis is tilted, and this tilt, combined with the Earth's orbit around the Sun, explains another periodic phenomenon experienced on Earth. What is this phenomenon?

   [1 mark]

   • AThe daily cycle of day and night
   • BThe changing seasons throughout the year
   • CThe phases of the Moon
   • DSolar eclipses

   (c)

   State the approximate time taken for the Earth to complete one orbit of the Sun, and the approximate time taken for the Moon to complete one orbit of the Earth.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A spacecraft engineer is calculating how the strength of the Earth's gravitational field changes as a satellite moves further away from the Earth's surface, and comparing this with the gravitational field strength at the surface of other planets.

   (a)

   A spacecraft engineer is calculating how the pull of Earth's gravity on a satellite changes as the satellite moves further from the Earth's surface. What happens to the strength of the Earth's gravitational field as distance from the Earth increases?

   [1 mark]

   • AIt stays exactly the same at all distances
   • BIt increases
   • CIt decreases
   • DIt becomes negative

   (b)

   The engineer compares the gravitational field strength at the surface of Earth with that at the surface of a much less massive planet at a similar distance from the Sun. Which statement correctly describes how the mass of a planet affects the gravitational field strength at its surface?

   [1 mark]

   • AOnly the Sun's mass affects gravitational field strength anywhere in the Solar System
   • BA more massive planet has a weaker gravitational field at its surface
   • CThe mass of a planet has no effect on its gravitational field strength
   • DA more massive planet has a stronger gravitational field at its surface

   (c)

   State two factors that determine the strength of the gravitational field at the surface of a planet, and explain why an astronaut would weigh less standing on the surface of a planet with a smaller mass than the Earth, even though their own mass has not changed.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A space agency is planning a robotic rover mission to Mars and must calculate the communication delay between Earth and Mars, using the average orbital distance between the two planets and the speed of light.

   (a)

   A space agency is planning a mission to Mars and must calculate how long radio signals will take to travel between Earth and Mars. Given that the average distance between the Earth and Mars is 2.25 x 10^11 m, and that light (and radio waves) travel at 3.0 x 10^8 m/s, calculate the time taken for a radio signal to travel from Earth to Mars, showing your working, and explain why mission controllers cannot use real-time (instant) control of a rover on Mars.

   [3 marks]

   (b)

   The space agency also wants to compare the average orbital speed of Mars with that of the Earth. Mars has an average orbital radius of 2.28 x 10^11 m and an orbital period of 687 days, while the Earth has an average orbital radius of 1.50 x 10^11 m and an orbital period of 365 days. Using the equation for average orbital speed, calculate the average orbital speed of Mars in metres per second (converting the orbital period to seconds), and state whether your answer confirms that planets further from the Sun have lower average orbital speeds than planets closer to the Sun.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A planetarium is designing a new exhibit explaining why the Earth experiences day and night, the seasons, and the Moon's changing cycle of phases, using models of the Earth, Moon and Sun to demonstrate these periodic cycles to visitors.

   (a)

   Describe, with reference to the Earth's rotation on its tilted axis and its orbit around the Sun, how each of these three periodic phenomena (day and night, the seasons, and the Moon's cycle of phases) is produced, making clear the different timescales involved in each.

   [6 marks]

   (b)

   The exhibit also includes an interactive display where visitors can calculate the average orbital speed of the Earth around the Sun and compare it with the Moon's average orbital speed around the Earth. Using the average orbital speed equation, and given that the Earth orbits the Sun at an average radius of 1.5 x 10^11 m with an orbital period of 365 days, and the Moon orbits the Earth at an average radius of 3.84 x 10^8 m with an orbital period of 27.3 days, calculate both average orbital speeds, and explain why the Earth's average orbital speed around the Sun is so much greater than the Moon's average orbital speed around the Earth.

   [6 marks]

   Total for question 4: 12 marks

End of questions