01 Key Concepts
SI Base Units
Meter (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for current, kelvin (K) for temperature, mole (mol) for amount of substance, candela (cd) for luminous intensity.
SI Prefixes
Prefixes scale units by powers of 10: kilo- (1000x), centi- (1/100), milli- (1/1000), micro- (1/1,000,000).
Derived Units
Combinations of base units, like the newton (N = kg*m/s^2) for force, or the joule (J = kg*m^2/s^2) for energy.
Significant Figures
The digits in a measurement that carry meaningful precision; more significant figures indicate a more precise measurement.
Unit Conversion
Converting a measurement from one unit to another using a known conversion factor, such as 1 km = 1000 m.
02 Key Formulas
- 1 km = 1000 m
- 1 kg = 1000 g
- 1 hour = 3600 s
03 Solved Examples
Example 1 Convert 5 kilometers to meters.
- Use the conversion factor 1 km = 1000 m.
- 5 * 1000.
Answer: 5,000 meters
Example 2 Convert 2,500 grams to kilograms.
- Use the conversion factor 1000 g = 1 kg.
- 2500 / 1000.
Answer: 2.5 kilograms
Example 3 What is the SI unit of force, and what base units does it combine?
- Force's SI unit is the newton (N).
- It combines mass, length, and time: N = kg*m/s^2.
Answer: Newton (N) = kg*m/s^2
04 Practice Questions
1Convert 3 km to meters.
3,000 m
2Convert 1,500 m to km.
1.5 km
3What does the prefix 'milli-' mean?
1/1000
4What is the SI base unit of time?
The second (s)
5Convert 4 hours to seconds.
14,400 s
📄 Units & Measurements — Downloadable Worksheet
10 questions with a full answer key. Grab the PDF to print, or try the interactive version in your browser.