1. Definitions
The scientific definition of work is a force exerted over a distance (work = force · distance)
work -
The scientific definition of energy is the ability to do work
energy -
The scientific definition of power is the rate at which work is done (power = work  time)
power -

2. The equation depends on the type of energy
Equations and Units
work
You must use the force component in the direction of the d when determining the work
Equation 
W = F · d
Unit 
joule {1 J = 1 N · m }
energy
Equation 
The equation depends on the type of energy
Unit 
joule or kilowatt·hour {1 kW·hr = 3,600,000 J }
power
Equation 
P = W  t
Unit 
watt {1 watt = 1 J/s } or horsepower {1 hp = 746 watts }

3. Types of Mechanical Energy
energy of motion ( KE = 1/2 mv2 )
KINETIC ENERGY (KE) -
moving objects, sound waves
POTENTIAL ENERGY (U) -
stored energy
There are two types of mechanical stored energy:
Gravitational potential energy (UG) -
energy stored by gravity ( UG = mgh )
wrecking ball
GPE is always a negative and large number when we look at the Earth and an object near its surface – usually, we’re concerned with changes in GPE in a given system, thus mgh.
Elastic potential energy (Us) -
energy stored by an elastic medium
( US = ½ kx2 )
where: k = spring constant
x = amount of stretch or compression
rubber band