The Earth And The Solar System (continued 2)
Overview
The Sun holds more than 99 percent of the mass of the Solar System, and that vast mass is what keeps eight planets, countless asteroids and long-tailed comets sweeping around it. The same gravity that gives you weight on Earth reaches across hundreds of millions of kilometres to hold whole worlds in orbit.
In this topic you will learn what controls a planet's gravitational field strength, calculate how long light takes to cross the Solar System, and see why the Sun's gravity keeps the planets in orbit. You will also explore how orbital speed changes with distance from the Sun and use conservation of energy to explain why a comet races when it is close to the Sun.
Objectives
- Know that the strength of the gravitational field (a) at the surface of a planet depends on the mass of the planet (b) around a planet decreases as the distance from the planet increases
- Calculate the time it takes light to travel a significant distance such as between objects in the Solar System
- Know that the Sun contains most of the mass of the Solar System and this explains why the planets orbit the Sun
- Know that the force that keeps an object in orbit around the Sun is the gravitational attraction of the Sun
- [Supplement] Know that the strength of the Sun’s gravitational field decreases and that the orbital speeds of the planets decrease as the distance from the Sun increases
- [Supplement] Know that an object in an elliptical orbit travels faster when closer to the Sun and explain this using the conservation of energy
Audio Lesson
Listen to this lesson in the app
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Flashcards
Quick recall practice on the facts this topic is tested on.
Practise these cards in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on The Earth And The Solar System (continued 2). Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- The gravitational field strength at the surface of a planet depends on the planet's: A. colour B. mass C. number of moons D. temperature Answer: B
- Light takes about how long to travel from the Sun to the Earth? A. 8 seconds B. 8 minutes C. 8 hours D. 8 days Answer: B
- The planets orbit the Sun because of: A. magnetic attraction B. the Sun's gravitational attraction C. the solar wind D. air resistance Answer: B
- As distance from the Sun increases, the orbital speed of a planet: A. increases B. decreases C. stays the same D. becomes zero Answer: B
- A comet in an elliptical orbit moves fastest when it is: A. farthest from the Sun B. closest to the Sun C. at constant distance D. outside the Solar System Answer: B
Work through these questions in the app
Work through these questions in the app
Recommended Books
Practice Mock Questions
Want to practice mock questions on The Earth And The Solar System (continued 2)? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
