Units & Dimensions
Welcome to the foundation of physics! Before we dive into the exciting world of motion, forces, and energy, we need to establish the language of physics - units and dimensions.
Physics is fundamentally about measurement and quantification. Every physical quantity we study has both a numerical value and a unit that gives it meaning.
The International System of Units (SI)
The International System of Units (SI) provides a standardized framework for measurement. The seven fundamental SI base units are:
- Length: meter (m)
- Mass: kilogram (kg)
- Time: second (s)
- Electric Current: ampere (A)
- Temperature: kelvin (K)
- Amount of Substance: mole (mol)
- Luminous Intensity: candela (cd)
All other units can be derived from these base units through multiplication and division.
Dimensional Analysis
Dimensional analysis is a powerful tool that helps us:
- Check if equations are physically meaningful
- Convert between different unit systems
- Solve problems systematically
For example, velocity has dimensions of [L]/[T], which means length divided by time.
Scientific Notation and Significant Figures
In physics, we often deal with very large or very small numbers. Scientific notation helps us express these numbers clearly and maintain precision through proper use of significant figures.
Remember: The precision of your final answer should reflect the precision of your measurements!