Cambridge IGCSE Physics Notes 6.1: Earth and the Solar System
Cambridge IGCSE Physics space notes on Earth, Moon, day, year, seasons, gravity, orbits, planets, minor planets, comets, and orbital speed.
Q: What does Cambridge IGCSE Physics Notes 6.1: Earth and the Solar System cover?
A: It follows official Cambridge Physics section 6.1 for syllabuses 0625 and 0972, with Core ideas separated from Supplement depth.
Solar-System motion is governed by gravity, with rotation explaining day, orbit explaining year, and axial tilt explaining seasons.
The ideas that organise this section
- Separate rotation on an axis from revolution in an orbit.
- Seasons result from axial tilt and changing sunlight angle, not large changes in Earth-Sun distance.
- Gravity supplies the inward force required for orbital motion.
Core route
Core candidates should be ready to describe, calculate, interpret, and apply the following:
- Describe Earth, Moon, and Solar-System structure and motions.
- Explain day, year, Moon phases, and seasons at the required qualitative level.
- Describe planets, minor planets, comets, and satellites.
Supplement route
Extended candidates study all Core content and add the following depth:
- Use orbital speed, radius, and period relationships.
- Explain changing comet speed qualitatively through gravitational energy changes.
- Relate gravitational field strength and orbital behaviour to mass and distance.
Formula route
- Relationship: orbital speed = 2 x pi x orbital radius / period.
Write the relationship before substituting. Convert units first, keep extra figures during working, and round only the final answer to sensible precision.
Build a connected model
In Earth and the Solar System, a strong answer connects the named quantity or model to observable evidence. Begin by defining the physical quantity in words or with its relationship. Identify which values are scalars and which require a direction. Represent the situation with a labelled diagram, graph, field pattern, ray or circuit when that makes the relationship visible. The representation is part of the reasoning: its labels, arrows and scale should agree with the written explanation.
For a calculation, write the governing relationship before substitution, convert prefixes and time units, keep unrounded values during working and attach the correct final unit. For a qualitative question, use a cause-link-consequence chain. Name what changes, state the physical mechanism that links the change to the system, and then give the measurable result. If two cases are compared, hold unrelated variables constant and use the same physical principle for both.
