Physics › Section A · The nature of science and physics › Topic A.2
Units, significant figures, and estimation
Every number in physics comes with a unit and a limit on how well it is known. This topic covers the SI units, how to convert between units, how many digits a result deserves, and how to make quick estimates that tell you whether an answer is sensible.
In this topic
- A number is not enough
- The seven SI base units
- Derived units and dimensional analysis
- Prefixes and scientific notation
- Worked example: converting units
- Accuracy, precision and uncertainty
- Counting significant figures
- Significant figures in calculations
- Worked example: a sprint on a measured track
- Worked example: an order-of-magnitude estimate
- Common mistakes to avoid
- Key takeaways
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