Physics Basics
Physics is the study of matter, energy, space, and time — the most fundamental level of how reality works. You don’t need to be a physicist to live on Earth, but understanding the basics helps you navigate the physical world.
Matter
Everything that has mass and takes up space is matter. Matter exists in four common states:
| State | Description | Example |
|---|---|---|
| Solid | Fixed shape and volume; tightly packed molecules | Ice, rock, wood |
| Liquid | Fixed volume, variable shape; flows freely | Water, oil, blood |
| Gas | Variable shape and volume; molecules spread out | Air, steam, smoke |
| Plasma | High-energy ionized gas | Stars, lightning |
Matter is made of atoms — tiny particles that are the building blocks of everything. Atoms combine into molecules.
Forces
A force is any push or pull that acts on an object. The fundamental forces:
Gravity
The force of attraction between objects with mass. The more massive an object, the stronger its gravitational pull. This is why:
- Objects fall downward on Earth
- Earth orbits the Sun
- The Moon orbits Earth
On Earth’s surface, gravity pulls everything at ~9.8 m/s² downward. This is why dropping things is reliably dangerous.
Friction
The force that resists the motion of surfaces in contact. Friction is why:
- Walking is possible (your foot grips the ground)
- Cars can brake
- Things slow down when sliding
Electromagnetism
The force between electrically charged particles. It underlies:
- All chemical bonds
- Light and other electromagnetic radiation
- Electrical technology (everything electronic)
Energy
Energy is the capacity to do work. It cannot be created or destroyed — only converted from one form to another (conservation of energy).
| Energy Type | Description | Example |
|---|---|---|
| Kinetic | Energy of motion | A moving car, a thrown ball |
| Potential | Stored energy (by position or state) | A book held up high |
| Thermal | Heat | A warm cup of coffee |
| Chemical | Stored in molecular bonds | Food, batteries, fuel |
| Electrical | Flow of electric charge | Electricity in wires |
| Radiant | Electromagnetic waves | Sunlight, X-rays |
Heat flows from hot objects to cold ones, never the reverse (Second Law of Thermodynamics).
Light
Light is electromagnetic radiation visible to the human eye. It travels at approximately 300,000 km per second — the fastest speed in the universe.
White light is actually a combination of colors, visible when split (by a prism or raindrops): Red, Orange, Yellow, Green, Blue, Indigo, Violet → the rainbow
Why This Matters for Chad
Understanding basic physics helps you:
- Know why things fall (gravity)
- Understand how cars, planes, and machines work
- Understand energy bills, fuel, and electricity
- Make sense of why some materials conduct heat or electricity
Related: The Scientific Method | Chemistry | What is Earth | Artificial Intelligence