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Fundamental Units (OCR A Level Maths: Mechanics)
Revision Note
Fundamental Units
What are fundamental units?
- Fundamental units or S.I. units are the international standardised units used around the world
- The three main units you will be using are:
- Length measured in metres (m) (also called displacement)
- 1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm
- Time measured in seconds (s)
- 1 hour = 60 minutes, 1 minute = 60 seconds
- Mass measured in kilograms (kg)
- 1 kg = 1000 g, 1 g = 1000 mg
- Length measured in metres (m) (also called displacement)
- All other quantities can be measured in units derived from S.I. units
Worked example
Examiner Tip
- Make sure you fully understand the definitions of all the words in this section so that you can be clear about what your exam question is asking of you.
- Make sure you are confident converting between fundamental S.I Units
e.g. 17 minutes and 42 seconds = 1062 seconds
2.4 km = 2400 m
86000 mg = 0.086 kg.
- Watch out for exam questions using non S.I. units such as feet and inches or miles per hour.
- Remember mass (measured in kg) is not a weight (a force measured in Newtons).
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