Units (Forces and Motion)

2 marks · Normal

Explain why it is important to use SI units such as kilogram, metre, and second when carrying out calculations in Physics.

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Using SI units ensures consistency and accuracy in calculations. It allows scientists to compare results and avoids mistakes caused by mixing different types of units.

Must show: Consistency explanation, Comparison between results, Reason for avoiding mistakes

Also accept: Using SI units allows everyone to use the same standard, so calculations are reliable and results can be checked, compared, or reproduced by others.

Common mistakes: Vague answers lacking specific reasons; Just saying 'because it's physics'

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Marking points

B1 · 1 mark · Clear statement about consistency/standardisation of SI units in Physics

B1 · 1 mark · States that SI units prevent calculation errors (e.g. due to mixing units) OR allows comparison/sharing of results across the world

Worked solution

Using SI units is important because it means everyone is using the same standard units for mass, length, and time; this avoids confusion or mistakes in calculations that could be caused by using different units. It also allows scientists to compare and share their results easily.