Energy

Energy is the capacity (or capability) to do work.

Energy is used or consumed when work is done.

The SI unit for energy is joule - J, where

1 J = 1 Nm

Imperial Units of Energy

• 1 J = 0.738 ft lb
• 1 ft lb = 1.356 Nm (J)

Energy Forms

There can be several forms of energy, including:

• Mechanical energy
• Heat or thermal energy
• Electrical energy
• Chemical energy
• Nuclear energy
• Light energy

Energy Efficiency

Energy efficiency is the ratio between useful energy output and input energy:

μ = Eo / Ei

where:

• μ = energy efficiency
• Eo = useful energy output
• Ei = energy input