Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Astrophysics
156 practice questions
Topics covered
Practice questions
31–40 of 78 · Normal
Question 31
3 marks · Normal
Answer and see the solution →The Moon has an orbital radius of 384,000 km and takes 27.3 days to orbit Earth once. Calculate the average orbital speed of the Moon in km/s. (1 day = 86,400 s).
Question 32
1 mark · Normal
Answer and see the solution →Describe what would happen to a satellite if it slowed down in its orbit.
Question 33
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 34
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 35
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 36
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).
Question 37
5 marks · Normal
Answer and see the solution →The table below shows the classification of some stars by their surface temperature and colour:
Star classification by temperature and colour Star class Surface temperature (K) Colour O more than 33 000 blue B 33 000 – 10 000 blue-white A 10 000 – 7 500 white G 6 000 – 5 200 yellow K 5 200 – 3 700 orange M 3 700 – 2 000 red (a)[1 mark]In which class would the Sun be placed? Give the class letter and colour.
(b)[2 marks]A star shines with a yellow-white colour. Estimate its surface temperature range using the table.
(c)[2 marks]Explain why a star that appears red is much cooler than a star that appears white.
Question 38
3 marks · Normal
Answer and see the solution →A student is looking at the night sky and notices some stars appear brighter than others. Explain why two stars of the same size and type can appear to have very different brightness as observed from the Earth.
Question 39
4 marks · Normal
Answer and see the solution →The Milky Way is the galaxy that contains our Solar System.
(a)[1 mark]Describe the shape of the Milky Way as seen from above.
(b)[1 mark]Where is the Solar System located within the Milky Way galaxy?
(c)[2 marks]Explain why we see many stars in the direction of the Milky Way band in the night sky.
Question 40
4 marks · Normal
Answer and see the solution →The following table shows three observed stars and their properties:
Observed star properties Star Apparent colour Surface temperature (K) A red 2 500 B blue 34 000 C yellow 5 900 (a)[1 mark]Which star is the hottest? Explain your answer.
(b)[1 mark]What is the star class of Star C? Use the class table from the syllabus.
(c)[2 marks]Describe the expected relationship between the colour of a star and its surface temperature.