Potential and kinetic energy

Potential Energy:
Potential energy exists whenever an object which has mass has a position within a force field. The most everyday example of this is the position of objects in the earth's gravitational field.
The potential energy of an object in this case is given by the relation:
PE = mgh
where
PE = Energy (in Joules)
m = mass (in kilograms)
g = gravitational acceleration of the earth (9.8 m/sec2)
h = height above earth's surface (in meters)



Kinetic Energy:
Kinetic Energy exists whenever an object which has mass is in motion with some velocity. Everything you see moving about has kinetic energy.
The kinetic energy of an object in this case is given by the relation:
KE = (1/2)mv2
where
KE = Energy (in Joules)
m = mass (in kilograms)
v = velocity (in meters/sec)
Conservation of Energy
This principle asserts that in a closed system energy is conserved. This principle will be tested by you, using the experimental apparatus below. In the case of an object in free fall. When the object is at rest at some height, h, then all of its energy is PE.
As the object falls and accelerates due to the earth's gravity, PE is converted into KE. When the object strikes the ground, h=0 so that PE=0, the all of the energy has to be in the form of KE and the object is moving it at its maximum velocity. (In this case we are ignoring air resistance).