ENERGY? WHAT IS IT?

ENERGY? WHAT IS IT?

Imagine that you're someone curious who is trying to understand the way nature behaves. And by nature, don't count yourself out. Everything in the universe is what I mean by nature. Nature behaves in a way that is impossible to understand or make complete sense of. This leads us to a series of questions which we'll think about someday else. 

What do you mean by energy?

Let's say you want to describe work you're doing in some kind of useful/meaningful way? How can we do so? Let us think about it by pushing a table. So what did you noticed? Nothing right? Try again. Anything you felt? See if you're asked to describe the pushing of table you can somewhat model it in this way: 

Work done while pushing = Something you applied to push * Distance you did that for

which makes some sense of what we're trying to do. You might say if I lift the same table up and down millions of times, doesn't that account as work? Unfortunately not in our definition. But this gets the job done to certain extent. Or possibly there's no better way to do so.

We now name that something you applied to push as "force". We also feel like we have control over that something. You can apply more of it or less of it. Depends on you.

So till now we have some vague understanding of how work is done. Force we apply results in some kind of work. If you think about it carefully not every force results to work. Think of applying force on the same table vertically from top. Of course it won't move. So here we have basic question that if I apply force of same strength, in which direction will the object move the most? Intuitively you say horizontally.

So we updated our work definition like this:

Work = Force * Displacement * cosθ

where θ is the angle between force and displacement

Wait a second how come cos(θ)?

If you think about this cos(0°), it is 1. So maximum force. Which is definitely what we want.

If we now want to know how are we able to do that work we are again trapped in tricky situation. For simplicity we define another quantity which we'll call "energy" which lets us do work. So now we say there is another quantity which enable us to exert force.

So now we have 

Energy→Force→Work 

We can therefore say it is something which is related to force and work.

Ah, but what exactly is energy?

Well, we don't know exactly what energy is. Where did it came from? Why does it exist? We surely don't know that for sure. Yes, it is a little bit strange concept and sometimes its hard for one to grasp sense of it. 

Isn't it something just we made up to fit the story?

That is what science is. We describe nature in a way that WE interpret it. Of course we try to verify it by experiments. Our assumption of energy may be completely false but as long as it is able to stack other ideas into it well enough, it is worthwhile to know about it.