What is Conservation of Energy?
Energy is one of the most fundamental concepts in all of science. It comes in many different forms — kinetic, gravitational potential, elastic potential, thermal, chemical, light, and sound — and it can transform from one form to another. But here is the remarkable thing: the total amount of energy never changes.
Energy cannot be created or destroyed. It can only be transformed from one form to another or transferred from one object to another. The total energy of a closed system remains constant.
This law is one of the most powerful and universal rules in physics. It applies to everything from a falling apple to a rocket launching into space. When you think energy has been "lost," it has actually been converted into a form that is harder to detect — most often thermal energy (heat).
Think of energy like money in a bank account. You can move money between accounts (transfer energy), convert dollars to euros (transform energy forms), but the total amount of money in the system stays the same. You can never create money out of nothing, and it never simply disappears.
Forms of Energy: A Quick Review
Before exploring how energy is conserved, it helps to be clear about the main forms of energy you will encounter in MYP Physics:
- Kinetic Energy (KE): The energy an object has because it is moving. A rolling ball, a flying bird, and a flowing river all have kinetic energy.
- Gravitational Potential Energy (GPE): The energy stored in an object due to its height above the ground. The higher an object is, the more GPE it has.
- Elastic Potential Energy: Energy stored in a stretched or compressed object, like a spring or a rubber band.
- Thermal Energy (Heat): The energy associated with the random motion of particles inside a material.
- Chemical Energy: Energy stored in chemical bonds, such as in food, fuel, or batteries.
- Sound Energy: Energy carried by vibrations travelling through a medium.
- Light (Radiant) Energy: Energy carried by electromagnetic waves such as visible light.
- Electrical Energy: Energy carried by moving electric charges.
In MYP 4, you will focus mainly on transformations involving kinetic energy, gravitational potential energy, and thermal energy, as these are the most common in mechanics problems.
In most real-world situations, energy transformations involve multiple forms at once. For example, a petrol engine transforms chemical energy into kinetic energy, thermal energy, and sound energy simultaneously.
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