SIMPLIFIED: "3.4: Conversation of Energy"

Link: https://phys.libretexts.org/Bookshelves/University_Physics/Mechanics_and_Relativity_(Idema)/03%3A_Energy/3.04%3A_Conservation_of_Energy 

Note: The image above was taken from the original article.

**In addition to conservation of energy, various types of energy are also covered in this simplified article

The linked article above describes the conservation of energy, and honestly, from the title, you can probably infer what the idea is: energy is conserved in a system. This literally means that if you have 10 total joules of energy in a system (joules is the unit for energy), then no matter what happens in the system, there will be 10 total joules of energy in the system.

Now, the linked article doesn’t cover the numerous types of energy, rather, it only covers the conservation of energy principle. Since this organization is all about simplifying concepts, I will also be covering some common types of energies that you should know. The first one is kinetic energy. If an object is MOVING AT ALL, it has kinetic energy, because kinetic energy is basically energy due to motion. The mathematical equation to calculate kinetic energy is: 

Kinetic Energy = ½ times mass times velocity². This means that the faster an object moves, the more kinetic energy it has, because increasing the value of velocity in the equation above would lead to a greater kinetic energy. Additionally, the more mass that an object has, meaning the more it weighs, would also lead to greater kinetic energy.

Another common type of energy is called potential energy. This is energy due to an object’s position. Here is the equation to calculate potential energy for an object on Earth: Potential Energy = mass times height times 9.8. Even if an object is at rest, it can have potential energy. For a better explanation of potential energy, think about it like this: an object sitting on top of a shelf has more potential energy than an object sitting on the floor, because the distance of the object on the shelf is greater than the object on the floor, meaning its height is a bigger number. Therefore, you could think about it like the object on the shelf as greater “potential” to fall more. 

Sometimes, energy is dissipated, which means energy turns into heat because of friction. This doesn’t mean that energy is lost or destroyed.

Now, once again, the conservation of energy principle states that the total amount of energy in a system is always conserved, meaning it never changes. However, the amount of EACH type of energy in a system CAN change. For instance, if a ball rests 10 meters above the floor on some shelf, then the ball ONLY has potential energy; it has no kinetic energy because it has 0 velocity. This means that the total amount of energy in the whole system is the same as the amount of potential energy of the ball. However, if this ball starts falling downward, then some of the potential energy turns into kinetic energy, because the ball now has velocity. The amount of kinetic energy therefore increases and the amount of potential energy decreases (the potential energy decreases because the height is decreasing), but the TOTAL amount of energy in the system stays the same. This means that when you add the amount of kinetic and potential energy together while the ball is falling, you will get the same amount of joules as when you calculate the amount of potential energy of the ball originally at its resting position.