- ENERGY:
Energy is the capacity (or ability) to do work; it is measured in units of work.
(In physics, "work" means moving things around, or moving a force through a distance.)
In the Metric system, energy is usually measured in Joules.
- Kinetic energy is the energy of motion. It can be measured as the amount of energy needed to stop the motion, or to initiate it.
- Potential energy is stored-up energy. The potential energy of an object high up can be converted into kinetic energy by dropping the object.
- CONSERVATION OF ENERGY:
First law of thermodynamics: In a closed system, energy is neither created nor destroyed; it can only be
transformed from one form to another.
Various forms of energy include mechanical energy,
electrical energy, chemical energy, thermal energy (heat), and others.
Examples: An electric fan converts electrical energy into mechanical energy.
A furnace converts the chemical energy of the fuel into heat energy.
- ENTROPY and RANDOMNESS:
Orderly arrangements generally have more energy because it takes energy to put things in regular order.
If you knock down or blow up something orderly, what remains is generally more disorderly (more random).
Entropy is a measure of randomness.
Second law of thermodynamics: The entropy (randomness) of the Universe is always increaing.
On a practical level, this means that a truly closed system is very hard to achieve:
Every energy transformation
results in some loss of random energy in the form of heat.
Example: When your electric fan converts
electricity into mechanical energy, it also get hotter (so there is always waste or inefficiency).
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