Friday, August 13, 2021

What is Physics?

Physics Index

Where are we going with this? The information on this page introduces the broad topic of physics by identifying different fields within it.

What is Physics?

Physics enjoys, within broader pop culture, the respect of being a brainy, high-level, impressive knowledge. That's nice. But… physics really can be accessible to anyone, and in fact, it is commonly used on a daily basis by a huge sector of society. Actually, anyone operating a machine or crossing a bridge, or sitting on furniture is relying on physics.

Physics need not be impossibly difficult. It's not like it's rocket science!

Wait! Actually, rocket science is physics!

Physics is the study of matter, energy, and time… and how those three things react and interact.

Modeling Reality

Taking a broad look at it, the purpose of physics is to create models (often involving math) that attempt to reliably explain the basic features of complex phenomena.

These models only describe a part of realty, but they help build hypotheses and help guide experimental design.

Physics includes many things: mechanics, heat, light and other radiation, sound, electricity, magnetism, the structure of atoms, outer space… and more!

There are a number of common ways that physics topics are grouped. For instance…

Mechanics: the study of forces and motions; motion and its causes; interactions between moving and non-moving objects.

Examples:

Moving objects

Falling objects

Friction

Weight

Spinning objects

Bridges

Fluid Mechanics: the study of mechanics related to liquids, gases, and plasmas and the forces on them.

Examples:

Hydraulic jacks

Piping

Boats

Hot-air balloons and blimps

Thermodynamics: the study of heat and its effect on matter including temperature, pressure, volume and heat transfer.

Examples:

Melting

Freezing

Engines

Refrigerators

Heat transfer

Vibrations and Waves: the study of mechanical waves through physical media

Examples:

Ocean waves

Earthquakes

Sound

Periodic Motion: the study of the motion that repeats in equal intervals of time.

Examples:

Pendulums

Springs

Optics: the study of the behavior and properties of light and its interaction with matter

Examples:

Mirrors

Lenses

Color

Cameras

Electromagnetism: the study of electricity and magnetism and the resulting fields of force; the radiation of electromagnetic energy.

Examples:

Xray

Cell phone signals

Relativity: a model or construct to explain observed phenomena, general and special relativity examines the universe, especially with regard to objects or particles moving at high rates of speed or where gravitational forces are extreme,

Examples:

Particle collisions

Particle accelerators

Atomic Physics: the study of atoms with regard to electrons and atomic nuclei.

Examples:

Electron configuration

Plasmas

Nuclear Physics: the study of atomic nuclei and their interactions.

Examples:

Fission

Fusion

Quantum Mechanics: describes (models) the physical properties of nature at the scale of atoms and subatomic particles.

Examples:

Atoms

Parts of atoms

Astrophysics: the study of the universe, galaxies, solar systems, planets and moons.\

Examples

Astronomy

Much of physics rubs up against or even overlaps with topics of chemistry, so you might see some things that seem familiar. However, the two subjects are subtly differentiated.

The Goal of Physics (reprised)

The goal of physics is to describe the physical world in terms of how matter and energy interact. The laws of physics grow out of basic concepts, assumptions, established relationships and equations that can predict how things behave.

How does that actually work?

Think of physics like this…

For any known relationship between objects, energy, and time, the laws of physics serve as a "because," so whatever conditions are present act like an "if" and the predicted outcome is the "then" such that…

Because [some relationship exists], if [some conditions are present] then [some outcome will occur].

Let's try it this way…

Because the distance an object will travel can be found using the equation

d = vt

(where d is the distance, v is velocity (rate of motion), and t is the elapsed time),

if a car travels at 20 m/hr for 3 hours

then it will have moved a distance of 60 miles.

The outcome (the then) of any situation (the if) will be determined by relevant laws of physics (the because).