Summary

• Energy is defined as the ability to do work.

• Energy has no mass and cannot be observed, but it can be quantified based on how much work is being done or could potentially be done.

• Energy is measured in joules, which have the symbol J.

• The two main categories of energy are kinetic energy and potential energy.

• Kinetic energy is active energy that involves some type of movement.

• It includes mechanical kinetic energy, thermal energy (heat), radiant energy (radiation), sound energy and electrical kinetic energy.

• Kinetic energy is directly usable and measurable.

• Potential energy is inactive energy that involves some type of energy storage.

• It includes gravitational potential energy, elastic potential energy, electrical potential energy, chemical energy and nuclear energy.

• Potential energy is only usable and measurable once it is converted into kinetic energy.

• All objects possess several forms of energy.

• The total energy of an object is the sum of all the kinetic and potential energy it contains.

• Energy transfer is the movement of the same type of energy from one location to another.

• Energy transformation is the conversion of energy from one form into another.

• The law of conservation of energy states that energy cannot be created or destroyed.

• Whenever energy is transferred or transformed, some energy is converted into heat energy.

• This means that the transfer and transformation of energy is not 100% efficient.

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