Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Motion in the Universe
55 practice questions
Topics covered
Practice questions
51–55 of 55
Question 51
4 marks · Easy
Answer and see the solution →Halley's Comet has an orbit that brings it close to the Sun, then takes it far out into the solar system. Meanwhile, Earth’s Moon orbits Earth at nearly constant speed.
(a)[2 marks]Describe the main difference in the orbit of a comet compared with that of a moon.
(b)[1 mark]State what happens to the speed of the comet as it moves closer to the Sun.
(c)[1 mark]Explain your answer to part b using ideas about forces in the solar system.
Question 52
6 marks · Normal
Answer and see the solution →The planet Mars and one of its artificial satellites both move in orbits around different objects. The table below gives the average orbital radius and time period of Mars around the Sun, and of a satellite around Mars.
(a)[1 mark]Orbital data for Mars and its satellite Object Orbits Average Orbital Radius (km) Time Period (days) Mars Sun 227,900,000 687 Satellite Mars 6,000 0.32 (b)[1 mark]State the name of the force responsible for keeping both Mars and the satellite in their respective orbits.
(c)[2 marks]Explain why the time period of orbit is much greater for Mars than for its satellite, even though both are in orbit due to the same force.
(d)[2 marks]Calculate the orbital speed of the artificial satellite around Mars. Give your answer in km/s. Use the formula: speed = (2 ) / , where is the orbital radius and is the time period in seconds.
Question 53
5 marks · Normal
Answer and see the solution →Consider a comet with a highly elliptical orbit around the Sun, and a moon with a nearly circular orbit around a planet.
(a)[2 marks]State two differences between the orbit of a comet and that of a moon in our solar system.
(b)[2 marks]Explain why the speed of a comet changes as it moves along its orbit, while the speed of a moon remains nearly constant.
(c)[1 mark]The average orbital radius of the moon is 400,000 km. If it takes 28 days to complete one orbit, calculate the average orbital speed of the moon. Give your answer in km/s.
Question 54
5 marks · Normal
Answer and see the solution →The table below shows some data about gravitational field strengths for two planets and their effect on the orbits of their moons.
(a)[1 mark]Planetary Data Planet Mass (Earth=1.0) Radius (Earth=1.0) Gravitational Field Strength (N/kg) Earth 1.0 1.0 10 Jupiter 320 11 23 (b)[2 marks]Explain, using the data, why gravity is stronger at the surface of Jupiter than at the surface of Earth.
(c)[2 marks]The moon of Jupiter orbits at an average radius of 422,000 km and completes one orbit in 1.8 days. Calculate the average orbital speed of this moon in km/s (show all working).
Question 55
5 marks · Normal
Answer and see the solution →A communication satellite is placed in orbit 36,000 km above Earth's surface. The radius of Earth is approximately 6,400 km.
(a)[1 mark]Calculate the total orbital radius of the satellite from the centre of the Earth.
(b)[2 marks]Explain why artificial satellites in low orbits move faster than satellites in high orbits above the same planet.
(c)[2 marks]The communication satellite takes exactly 24 hours to complete one orbit. Calculate its average orbital speed in km/s (show all working).