Introduction to Physics

 

"Physics."

A word which certainly has been haunting many students all around the world like a ghost, inciting fear in their heart whenever they hear that word. It's also one of the most hated things in many schools together with math.

How in the world does it happen? What has this "physics" done that it becomes hated across the world? 

What is "physics" actually?

Does it have something to do with physical things, perhaps? With the physical world? 

...

...

...

The answer is: "Yes, it does."

Physics is (as far as the writer knows and understands) a branch of natural science concerning physical matters and their behaviors.

The main goals of the so-called physics are to identify a limited number of the fundamental laws which govern natural phenomena and use them to develop theories to predict the results of future experiments

And to do so, observations and experiments are needed. Taking from the main goals alone and how to approach the goals, physics is supposed to be only a collection of concepts and fundamental laws which govern the nature in accordance with our observations, experiments, and logic.

But how does it become hated?

The answer lies in math, the abstract science of numbers, which is often used to explain physics.

The number of complex-looking formulae which the students apparently have to memorize makes it difficult for many of them to study physics.

Very often, this kind of thought will pop up in their minds: "Why does physics always involve math? It's so troublesome."

But hold up for a moment. If you're one of them, you should start to really think about it, too.

"Why does physics always involve math?"

This question will lead to other questions: "If physics indeed is just a collection of laws and concepts, then why must it involve those complex-looking formulae?" and finally "What does math really have to do with physics? How are they connected?"

Now, think about this. To know the laws which govern the nature, a direct observation or experiment to the nature must be necessary, don't you think so? It's like when we wanted to know whether our pen or our book which would hit the ground first, we'd bring our pen and our book on our hands then release them from approximately the same height and see which would hit first.

When we did a simple experiment like that, we always measured at least a thing or two from our experiment (i.e. the time taken, the height, etc.) to determine if our theories, our hypotheses—the predictions we’ve made beforehand—were true, right?

In order to connect our theories with the actual result we’ve measured from our experiment, we’ll need something—a bridge to connect them. And that exact bridge is math, a language to express the fundamental laws used in developing our theories.

But, how does math connect theories with experiments?

Think about the simple math stuff you know, like addition, subtraction, multiplication, etc. It's based on logic, isn't it? Adding things to the existed things is called addition, taking things from the existed things is called subtraction, and so on.

Physics works the same way. When something gets bigger when we increases something else, it indicates proportionality, although it's not always the case. When something gets smaller when we increases something else, it indicates inverse proportionality. And there are often times when this proportionality is not a linear proportion, but an exponential proportion.

This characteristic of physics makes math the only way to express the fundamental laws that we've got from our experiments.

An example:

Why does speed equal distance over time? Of course, it is because of the basic definition of "speed" itself: "how fast an object moves".

Because the speed describes "how fast", it must have a relation with time.

Because the speed describes "how an object moves", it must have a relation with position and/or distance.

What does make an object moves faster? If it can travel a long distance over a short time interval, it's fast. And if it travels a short distance over a long time interval, it's slow. 

The longer the distance traveled in the same time interval, the faster it becomes. And the shorter the time taken for traveling the same distance, the faster it becomes.

This indicates a direct proportionality between speed and distance and an inverse proportionality between speed and time.

$$ speed \propto distance $$

$$ speed \propto \frac{1}{time} $$

Which then creates a formula we now are familiar with: \( v = \frac{d}{\Delta t} \) where \( v \) is the speed of the object, \( d \) is the distance traveled by the object, and \( \Delta t \) is the time interval taken by the object.

It then raises another definition for speed: "a distance traveled by an object in one unit of time." And we can see that it perfectly agrees with our previous definition of speed! Because, more distance traveled in one unit of time means a faster speed.

The true beauty of physics lies in its concepts and the logics behind them. As we understand more and more of fundamental concepts, the formulae will slowly make more sense to us.

That's why you shouldn't memorize the formula, but you should understand the formula.

And this concludes my very short introduction to physics.

~~~