Our use of language in everyday life is often quite different to the language of scientists. This can sometimes be confusing because what scientists mean and what most people mean are two different things. Scientists need to be very precise so that when they use a word it always means the same thing. One word that can be a problem is ‘energy’.
When people talk about energy, they often talk about ‘using energy’ or ‘losing energy’. Students (and adults) can develop the idea that things ‘use up’ energy. They imagine that something has lots of energy, and then as the object functions, it uses up energy until it runs out. This is perpetuated by such phrases as ‘we are running out of energy’ when referring to exercising hard (say, running) or when referring to using up natural energy resources (like oil).
In fact, energy is transformed from one form to another. It is not used up or lost. A fundamental belief in science is the ‘law of conservation of energy’. This means that energy in the universe is a constant – it cannot be created nor destroyed. In photosynthesis solar energy is transformed into chemical energy. This is a key step in any food chain.
Sometimes, students think food is energy or electricity is the only form of energy. It is actually the chemical energy in food that enables us to carry out life’s processes. Similarly, it is electrical energy that, when transformed into heat and light energy, allows a light bulb to function. Energy is what causes things to happen.
Energy can be found in a number of different forms such as chemical energy, electrical energy, heat (thermal energy), light (radiant energy), mechanical energy and nuclear energy.
Energy can also be divided into two main types:
- Stored energy is called potential energy.
- Moving energy is called kinetic energy.
Explore these ideas further in the article What is energy?