Energy

What is energy?

Ability or capacity to do work

Potential Energy

Stored energy resulting from the relative position of matter rather than its motion

Kinetic Energy

A body or particle's energy due to its motion

Open & Closed Systems

• An open system exchanges energy with its surroundings
• A closed system does not receive or emit energy
• Thermodynamically, the Earth is an open system
• However, materially, it is a closed system

First Law of Thermodynamics

First Law of Thermodynamics

• Conservation of energy
• Energy can be transformed, but not destroyed (or created)
• Change in internal energy equals heat added to the system minus work done by the system

Second Law of Thermodynamics

Second Law of Thermodynamics

• Law of entropy
• With every transformation, some energy is lost to heat
• No conversion is 100% efficient
• Heat tends to flow from hot to cold regions and energy tends to flow from mechanical to heat energy
• Any flow against these trends must be compensated by an offset in the opposite direction (Gamow, 2006)