Physics needs measurements that everyone understands, no matter where they are. That’s where the SI system comes in. It’s the standard way we measure things in science.

What are SI Units?

The International System of Units (SI) is the main way to measure things in science. Think of it as the common language for numbers in physics. It helps scientists all over the world share their work clearly.

The SI system has seven basic measurements, each with its own standard unit:

  1. Length: Meter (m)
  2. Mass: Kilogram (kg)
  3. Time: Second (s)
  4. Electric Current: Ampere (A)
  5. Temperature: Kelvin (K)
  6. Amount of Substance: Mole (mol)
  7. Light Brightness: Candela (cd)

All other units in physics (like for speed, push, or energy) are built from these seven basic units. For example, speed is measured in meters per second (m/s), which uses ‘meter’ and ‘second’ from the basic list.

Interactive Match: SI Units

Test your knowledge of SI base quantities and their units by matching them.

Click a quantity and then its matching SI unit. Match all pairs to complete!

Why SI Units Matter

  • Everyone Understands: Scientists and engineers all over the world can easily understand each other’s work.
  • No Confusion: Using the same system stops mistakes and mix-ups that happen when different ways of measuring are used.
  • Easy to Use: The SI system works with tens (like 10, 100, 1000), which makes changing units very simple.
  • Building Blocks: These basic units are the starting point for all other measurements and calculations in physics.

Audio Explanation

Prefer to listen? Here's a quick audio summary of SI Units and Base Quantities.

💡 Quick Concept Check:

What is the SI base unit for mass?

Click to Reveal Answer
The SI base unit for mass is the kilogram (kg).
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