There are 9 types of energy:
- chemical energy - energy stored in fuel (ie. food) which is released when chemical reactions take place
- kinetic energy - energy of a moving object
- gravitational potential energy (GPE) - energy an object contains due to its position
- elastic (strain) potential energy - energy stored in an object that is being stretched, squashed, twisted, you name it!
- electrical energy - energy transferred by an electric current
- thermal (heat) energy - energy of an object due to its temperature. This is partly because of the random kinetic energy of the particles of the object.
- nuclear energy - energy stored in an atom’s nucleus
- light energy - energy transferred through waves and light particles (photons)
- sound energy - energy transferred via sound waves
The Law of Conservation of Energy states that energy cannot be created or destroyed; however, it can be transformed or transferred.
Machines transfer energy for a purpose. The only problem is that not all energy transferred is useful to us because it doesn’t always go where we want it in the form we wanted it in.
Energy Supplied = Useful Energy Delivered + Energy Wasted
Useful Energy Output
Device Efficiency = ----------------------------
Energy Supplied as Input
Efficiency can be visually represented by a Sankey Diagram (pictured above). No machine can be more than 100% efficient because we can never get more energy from a machine than we put into it. An inventor in 19th century America claimed to have made a machine that gave out useful energy without energy being supplied to it. It was later discovered he had a partner pedaling away beneath the ground to supply it with energy!
