# A student writes down four statements about physical quantities and their units. For each statement, explain whether the student is correct or incorrect, giving a reason. Statement 1: 'Momentum is measured in kg m/s.' Statement 2: 'The spring constant has the unit metres per newton (m/N).' Statement 3: 'Gravitational field strength is measured in N/kg.' Statement 4: 'The moment of a force is measured in newton metres (Nm).'

> Pearson Edexcel International GCSE Physics (4PH1) — 1.1 Units · Explain · 4 marks

## Mark scheme (4 marks)

1. Statement 1 is correct: momentum = mass × velocity, so the unit is kg m/s.
2. Statement 2 is incorrect: the spring constant k = F/x, so its unit is N/m (newtons per metre), not m/N.
3. Statement 3 is correct: gravitational field strength is the force per unit mass, giving units of N/kg.
4. Statement 4 is correct: moment = force × perpendicular distance from pivot, so the unit is N × m = Nm.

## Key terms

- [momentum](https://www.gradenine.co.uk/glossary/momentum)
- [spring constant](https://www.gradenine.co.uk/glossary/spring-constant)
- [gravitational field strength](https://www.gradenine.co.uk/glossary/gravitational-field-strength)
- [moment](https://www.gradenine.co.uk/glossary/moment)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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/a-student-writes-down-four-statements-da075606) · Published by Druglandscape Ltd.