What is the law of conservation of energy?

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed.

In more detail, this fundamental principle of physics means that the total amount of energy in a closed system remains constant over time. Energy can change forms, such as from kinetic energy (the energy of motion) to potential energy (stored energy), or it can be transferred from one object to another, but the total energy remains the same. For example, when you ride a bicycle down a hill, the potential energy you have at the top of the hill is converted into kinetic energy as you speed up going down.

This law is crucial in understanding various physical processes and systems. For instance, in a roller coaster, the energy is continuously converted between potential and kinetic forms. At the highest points, the roller coaster has maximum potential energy and minimum kinetic energy. As it descends, the potential energy decreases while the kinetic energy increases, making the roller coaster move faster.

Another example is in electrical circuits. When you switch on a light bulb, electrical energy is converted into light and heat energy. The total energy before and after the switch is flipped remains the same, but it has changed forms.

Understanding the law of conservation of energy helps us to analyse and predict the behaviour of different systems, whether it's in mechanical systems, electrical circuits, or even biological processes. It is a foundational concept that underpins much of what we study in physics and helps us to solve problems by keeping track of energy transformations and transfers.