Two Types of Energy
There are two main types of energy in the world: Potential energy and Kinetic energy. The two types work together, often switching back and forth between one type and another. Basically, potential energy is energy that is waiting to be used, and kinetic energy is energy that is being used. But there's a little more to it than that.
Potential Energy
Potential energy is energy that has been stored up and is currently waiting to be used. Potential energy comes in three different forms:
1. Gravitational- Gravitational potential energy is stored up as an object rises. The further off the ground an object is, the more potential energy it has. This is because, while gravity pulls on all objects the same, objects pick up more and more speed the longer they fall. So, an object that falls from 100 feet is going to be going faster when it hits the ground than an object that fell from 20 feet. The faster it is going, the harder it hits and the more energy it has.
1. Gravitational- Gravitational potential energy is stored up as an object rises. The further off the ground an object is, the more potential energy it has. This is because, while gravity pulls on all objects the same, objects pick up more and more speed the longer they fall. So, an object that falls from 100 feet is going to be going faster when it hits the ground than an object that fell from 20 feet. The faster it is going, the harder it hits and the more energy it has.
2. Elastic - Elastic potential energy comes from objects that can be stretched and that will rebound back to their original shape, like a rubber band. When you stretch a rubber band, or pull it back like you're going to shoot it at someone, you are giving it elastic potential energy. The further you stretch it, the more potential energy it has and the farther it will fly when you let go of it.
3. Chemical - Chemical potential energy is just that, energy that can be used in a chemical reaction. It is also the most varied of the potential energies. Chemical energy sources include things like batteries and food. Batteries are obvious. Chemicals inside the battery are connected when inserted into a device and undergo a chemical reaction until they run out. Food is a little more complicated. Basically, your body completes a lot of chemical reactions after you eat a piece of food and uses it for energy. That's why, if you don't eat for a while, you start to feel weak.
3. Chemical - Chemical potential energy is just that, energy that can be used in a chemical reaction. It is also the most varied of the potential energies. Chemical energy sources include things like batteries and food. Batteries are obvious. Chemicals inside the battery are connected when inserted into a device and undergo a chemical reaction until they run out. Food is a little more complicated. Basically, your body completes a lot of chemical reactions after you eat a piece of food and uses it for energy. That's why, if you don't eat for a while, you start to feel weak.
Kinetic Energy
Kinetic energy is the energy of motion. Anything that is moving has kinetic energy. How much kinetic energy they have is based on their speed. The faster an object is moving, the more kinetic energy it has. Mass also plays a role. Objects with higher mass have more kinetic energy than object with lower mass. This is because kinetic energy is based on how fast each particle in the object is moving. Objects with more particles (more mass) have more kinetic energy.
Back and forth, Up and Down
As mentioned before, energy can be transferred back and forth from potential to kinetic and back to potential. This cycle, in a perfect world, could keep going forever. The easiest way to explain this is with an object that almost everyone is familiar with: a roller coaster. Bet you didn't know amusement parks were experts in physics, huh?
The amount of energy in any object can be divided into potential and kinetic energy at any given time. So, instead of working with big complicated numbers, lets just talk percentages. If an object has all potential and no kinetic energy, we would say that 100% of the energy is potential and 0% is kinetic.
In the diagram above, a cart on a racetrack is labeled at four different points. Notice that when the cart is at the highest point on the track, all of its energy is potential. This is the most potential energy it will ever have. This is because that very first hill on a roller coaster, always the highest one, gives the roller coaster cart all of its energy for the whole ride. That's why it is always at the beginning. And because it stops for just a moment at the top of that hill, the cart has no (0%) kinetic energy.
As the cart begin to fall down that first hill, it is losing potential energy as it gets closer to the ground (refer back to gravitational potential energy to see why). At the same time, that potential energy it is losing is causing it to gain speed, thus gaining kinetic energy. Halfway down the hill, half of the energy has been converted, meaning it has turned 50% of its potential energy into kinetic energy. By the time the cart has reached the bottom of the hill, all of the potential energy has been converted into kinetic energy, meaning the cart is moving as fast as it can. However, this speed and momentum carries it up the next little hill, meaning it will lose a little bit of speed as it climbs and convert part of the kinetic energy back into potential energy.
Isn't physics fun!?
In the diagram above, a cart on a racetrack is labeled at four different points. Notice that when the cart is at the highest point on the track, all of its energy is potential. This is the most potential energy it will ever have. This is because that very first hill on a roller coaster, always the highest one, gives the roller coaster cart all of its energy for the whole ride. That's why it is always at the beginning. And because it stops for just a moment at the top of that hill, the cart has no (0%) kinetic energy.
As the cart begin to fall down that first hill, it is losing potential energy as it gets closer to the ground (refer back to gravitational potential energy to see why). At the same time, that potential energy it is losing is causing it to gain speed, thus gaining kinetic energy. Halfway down the hill, half of the energy has been converted, meaning it has turned 50% of its potential energy into kinetic energy. By the time the cart has reached the bottom of the hill, all of the potential energy has been converted into kinetic energy, meaning the cart is moving as fast as it can. However, this speed and momentum carries it up the next little hill, meaning it will lose a little bit of speed as it climbs and convert part of the kinetic energy back into potential energy.
Isn't physics fun!?