Hey, guys. So in a previous video, we talked about lots of different energy types. We said that energy exists in many different forms in the universe, and more importantly, it always gets shuffled or transformed between types. We have heat and light and sound and all that good stuff. So we're going to be taking a look in much greater detail at some of these types of energies and do math with them. So in this video, I just want to give you sort of a brief overview of these kinds of types of energies. Let's check it out. It basically breaks down to 2 different subcategories. We have mechanical energy and non-mechanical energy, which is kind of just a blanket term for everything that's not in the first group, and it includes things like thermal energy. Probably the biggest one that we'll talk about there is friction. So if you, like, rub your hands together, that's friction and you generate heat. And then much later on, we'll talk about things like electrical and nuclear and light and all that good stuff. So the ones that we'll be really focused on are mechanical energies, and that breaks down to 2 different subcategories as well. We have kinetic, which is written by the symbol K, and we have potential, which is written by U. And a quick way to understand mechanical energy is actually this is the combination of your kinetic and your potential energy.

So let's talk about kinetic energy. This is really just the energy due to an object's speed. So if you have some mass and you have some velocity or some speed, then you have some energy. That's basically due to your motion. Now potential energy, we'll get back to this in just a second here, also breaks down into 2 main types, and we'll be taking a look at these as well. We have elastic, which is sometimes called spring energy. We also have gravitational potential energy.

So let's talk about springs. An easy way to understand this is to imagine that you have a box like this and you're pushing up against the box and basically, what happens is it stores some energy because when you release your hand, the spring pushes back on the box and then it shoots it out to the right like this. So what happens is by pushing up against the box, you've stored some elastic potential energy that's kind of like stored inside of the spring and when you let go, it gets released. And then the box finally has some speed and therefore, it has some kinetic energy. So you've transferred, elastic to kinetic energy. Alright? So elastic energy is really just due to a spring's deformation. You're either compressing it or stretching it or something like that.

Let's talk about gravitational potential energy. It's a similar idea except instead of due to compression, it's due to actually an object's height. So imagine that you take a box and you lift it way, way above your head. You give it some initial heights like this, and then you let it go. Well, what happens is the force of gravity, your mg, starts pushing or pulling this box down. And as it does that, it starts to gain some speed and it loses height. So at some point later, it has a lower height like this, but it's finally gained some speed. So here what you've done is you've basically stored some energy by lifting the box above your head and then gravity gives it, you know, sort of some velocity as it pulls it down. So you've stored some gravitational potential energy. And then as gravity pulls it down, you're trading sort of heights as you go down, but you're picking up speed and so you're picking up kinetic energy.

And so, really, there's actually something that's common between these two types of potential energy. So one way to think about potential energy is that you've kind of stored this energy that later on gets transferred to something else, and this is stored energy that's due to an object's position. So for springs, it's either the deformation like the, you know, so the deformation of the spring or for gravitational potential, it's due to the height above the floor. Alright? So this section is really important because we're going to see that all of these energies, gravitational, elastic, and even kinetic, are all going to start to get sort of transferred between each other. Alright? So that's basically it for this one, guys. Let me know if you have any questions.