Energy

Kinetic- Associated with an object by virtue of its motion.

Potential- The energy an object has by virtue of its position in a field of force.

Internal- The sum of potential and kinetic energies of the particles making up a subject.

The kinetic energy of an object depends on mass and speed. 

Atoms and Molecules have mass and are moving about, therefore they possess kinetic energy.  

1000J=1k

1 cal=4.184J 

Position (such as height) in a field of force  (such as gravity.)

 Water at the top of a damn is at a relatively high position in a field of force.

Where m=mass, g=gravitational constant (9.8m/sec²  and h is the height in this case relative to sea level.

E_p=mgh 

The energy of the particles making up a substance.

The total energy of a system is the sum of its kinetic energy, potential energy and internal energy (U).

E tot = E_k + E_p + u