Orbits and Gravity
IGCSE Edexcel Physics
8.3-8.5 Orbits and Gravity
Key Concepts:
Gravity provides the centripetal force for orbits. Orbits differ for planets, moons, and comets.
Section A: Gravity
1. Explain why $g$ is different on the Moon compared to Earth.
[2]
2. Explain how gravity causes a satellite to orbit Earth.
[3]
Section B: Orbit Types
3. Describe differences in orbits of comets, moons, and planets.
[3]
Total marks: 8
Mark Scheme
1.
Moon has lower mass so weaker gravitational field [2]
2.
Gravity provides centripetal force, changing direction of velocity [3]
3.
Comets elliptical, planets nearly circular, moons orbit planets [3]