Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Motion in the Universe
55 practice questions
Topics covered
Practice questions
21–27 of 27 · Easy
Question 21
3 marks · Easy
Answer and see the solution →The table shows some information about two planets:
Planet information Planet Mass (Earth=1) Radius (Earth=1) Planet A 1.5 1.0 Planet B 1.0 2.0 (a)[2 marks]Which planet has the higher gravitational field strength at its surface? Explain your answer.
(b)[1 mark]Which planet would an object weigh less on? Give a reason.
Question 22
3 marks · Easy
Answer and see the solution →A moon orbits its planet at a radius of 450,000 km. It takes 40 days to complete one orbit.
(a)[1 mark]Convert the orbital period into seconds.
(b)[2 marks]Calculate the average orbital speed of the moon in km/s. Give your answer to 2 significant figures.
Question 23
2 marks · Easy
Answer and see the solution →The following table shows orbital radii and periods for two satellites orbiting the same planet.
Satellite data Satellite Orbital radius (1000 km) Period (h) X 15 7 Y 30 28 (a)[1 mark]Which satellite orbits closer to the planet? Support your answer using data from the table.
(b)[1 mark]Explain which satellite has the greater orbital speed.
Question 24
4 marks · Easy
Answer and see the solution →The planet Venus and a space probe orbiting Earth both move in nearly circular orbits because of gravity.
(a)[1 mark]Name the force responsible for keeping Venus and the space probe in orbit.
(b)[2 marks]Explain why Venus moves faster in its orbit than Neptune does.
(c)[1 mark]State one difference between the orbit of the space probe and the orbit of a comet around the Sun.
Question 25
4 marks · Easy
Answer and see the solution →A satellite is placed in orbit at a height where the gravitational field strength is much smaller than on Earth’s surface.
(a)[2 marks]Explain why the satellite stays in orbit instead of falling straight towards the Earth.
(b)[2 marks]Calculate the orbital speed of the satellite if it travels along a circular path of radius m and completes one orbit in 24 hours. Give your answer in to two significant figures.
Question 26
4 marks · Easy
Answer and see the solution →The table below shows the gravitational field strength on the surface of different planets:
Planet Gravitational field strength (N/kg) Earth 10 Mars 4 Jupiter 23 Venus 9 (a)[1 mark]Which planet has the strongest gravitational field strength?
(b)[2 marks]A 60 kg object is placed on Mars. Calculate its weight on the surface of Mars.
(c)[1 mark]Explain why the weight of an object on Jupiter is more than that on Earth.
Question 27
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.