Motion In The Universe
Aperçu
Look up on a clear night and you are staring into the same universe that ancient sailors used to navigate and that modern telescopes are still mapping. From our nearest neighbour, the Moon, to galaxies billions of light-years away, the universe is organised into a hierarchy of structures held together by gravity.
In this lesson you will learn how planets, moons, comets and asteroids move through the solar system, why some orbits are circular and others are stretched, and how to calculate the speed of any orbiting body. These ideas appear regularly on Edexcel Papers 1 and 2, often as calculation or comparison questions.
Objectifs
- Know that the universe is a large collection of billions of galaxies, a galaxy is a large collection of billions of stars, and our solar system is in the Milky Way galaxy
- Understand why gravitational field strength, g, varies and know that it is different on other planets and the Moon from that on the Earth
- Explain that gravitational force causes moons to orbit planets, planets to orbit the Sun, artificial satellites to orbit the Earth, and comets to orbit the Sun
- Describe the differences in the orbits of comets, moons and planets
- Use the relationship between orbital speed, orbital radius and time period: orbital speed = 2 x pi x orbital radius / time period
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Note de cours
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Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur Motion In The Universe. Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à lépreuve. Cette section propose une variété de pratiques des questions conçues pour renforcer votre compréhension et vous aider à évaluer votre compréhension de la matière.
Vous rencontrerez un mélange de types de questions, y compris des questions à choix multiple, des questions à réponse courte et des questions de rédaction. Chaque question est soigneusement conçue pour évaluer différents aspects de vos connaissances et de vos compétences en pensée critique.
Utilisez cette section d'évaluation comme une occasion de renforcer votre compréhension du sujet et d'identifier les domaines où vous pourriez avoir besoin d'étudier davantage. Ne soyez pas découragé par les défis que vous rencontrez ; considérez-les plutôt comme des opportunités de croissance et d'amélioration.
- Which of the following correctly describes the structure of the universe? A) Stars contain galaxies which contain solar systems B) The universe contains galaxies which contain solar systems C) Solar systems contain galaxies which contain stars D) Galaxies contain universes which contain stars Answer: B
- What happens to the orbital speed of a planet as its distance from the Sun increases? A) It increases B) It stays the same C) It decreases D) It doubles Answer: C
- Which type of orbit do comets follow around the Sun? A) Circular B) Slightly elliptical C) Highly elliptical D) Parabolic Answer: C
- The gravitational field strength on the Moon is about 1.6 N/kg. What is the weight of a 50 kg object on the Moon? A) 50 N B) 80 N C) 500 N D) 31.25 N Answer: B
- What provides the centripetal force that keeps a planet in orbit around the Sun? A) The planet's own rotation B) Friction with space dust C) Gravitational attraction between the planet and the Sun D) Magnetic force from the Sun Answer: C
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Livres recommandés
Pour aller plus loin, ressources libres
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Section de manuel
Satellites and Kepler’s Laws: An Argument for Simplicity
Examples of gravitational orbits abound. Hundreds of artificial satellites orbit Earth together with thousands of pieces of debris. The Moon’s orbit about Earth has intrigued humans from time immemorial. The orbits of planets, asteroids, meteors, and comets about the Sun are no less interesting. If
"College Physics: Satellites and Kepler’s Laws: An Argument for Simplicity" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/6-6-satellites-and-keplers-laws-an-argument-for-simplicity. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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Section de manuel
Newton’s Universal Law of Gravitation
What do aching feet, a falling apple, and the orbit of the Moon have in common? Each is caused by the gravitational force. Our feet are strained by supporting our weight—the force of Earth’s gravity on us. An apple falls from a tree because of the same force acting a few meters above Earth’s surface
"College Physics: Newton’s Universal Law of Gravitation" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/6-5-newtons-universal-law-of-gravitation. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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