Energy is a word with more than one meaning.
- Mostly it is used in science to describe how much potential a physical system has to change. In physics, energy is a property of matter. It can be transferred between objects, and converted in form. It cannot be created or destroyed.
- It may also be used in economics to describe the part of the market where energy itself is harnessed and sold to consumers.
- In ordinary language, the word is used to describe someone acting or speaking in a lively and vigorous way.
Scientific energy[change | change source]
In science energy is something that can do work.
There are two basic forms of energy:
Conservation of Energy[change | change source]
Conservation of matter and energy[change | change source]
Scientists now know that matter can be made into energy, and energy into matter, through processes like nuclear fission and nuclear fusion. The law of conservation of energy has therefore been extended to become the Law of conservation of matter and energy. Albert Einstein was the first to mathematically derive this in the formula E = mc2.
Example[change | change source]
A stone is thrown upwards and falls to the ground.
- human throws the stone: energy store in muscles= chemical energy
- stone moves upwards= kinetic energy
- height of stone above ground= potential energy
- stone falls to ground= kinetic energy
- stone hits ground= thermal energy/sonic energy
Types of energy[change | change source]
Scientists have identified many types of energy, and found that they can be changed from one kind into another. For example:
- Light energy
- Sound energy
- Renewable energy
- Solar energy
- Nuclear energy
- Elastic energy
- Gravitational potential energy
- Kinetic energy
- Dark energy
- Hamiltonian mechanics
- Internal energy
Measuring energy[change | change source]
As in other kinds of measurements, there are measurement units. The units of measurement for measuring energy are used to make the numbers meaningful.
Some scientific units of measurement[change | change source]
Related pages[change | change source]
References[change | change source]
|Wikimedia Commons has media related to: Energy|
- Woolley, Steve. Edexcel IGCSE Physics Revision Guide. Pearson Education. p. 49. .