# Explain why it is important to use the correct SI unit when recording a measurement, and state the SI unit for each of the following: energy, electric charge, and pressure.

> Edexcel GCSE Physics (1PH0) — 1.1 Key concepts of physics · Explain · 4 marks

> A student records the speed of a car as '30' without writing any unit. Another student records the same speed as '30 m/s'.

## Mark scheme (4 marks)

1. Without a unit (or with an incorrect unit), a measurement has no meaning / cannot be understood / cannot be compared by other scientists
2. The SI unit for energy is the joule (J)
3. The SI unit for electric charge is the coulomb (C)
4. The SI unit for pressure is the pascal (Pa)

## Key terms

- [SI unit](https://www.gradenine.co.uk/glossary/si-unit)
- [energy](https://www.gradenine.co.uk/glossary/energy)
- [electric charge](https://www.gradenine.co.uk/glossary/electric-charge)
- [pressure](https://www.gradenine.co.uk/glossary/pressure)

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-it-is-important-to-8470b198) · Published by Druglandscape Ltd.