Introduction: What Is Mechanical Energy?
One of the most powerful ideas in all of physics is deceptively simple: energy cannot be created or destroyed — it can only change form. This principle, the law of conservation of energy, allows us to predict and explain the behaviour of everything from a bouncing ball to a roller coaster plummeting down a track.
Before we explore conservation, we need to be clear about what we mean by mechanical energy.
The total energy of a system associated with its motion and position. It is the sum of kinetic energy, gravitational potential energy, and elastic potential energy:
Each of these three components plays a different role:
- Kinetic energy (): energy a body has because it is moving
- Gravitational potential energy (): energy a body has because of its position in a gravitational field
- Elastic potential energy (): energy stored in a stretched or compressed spring (or elastic object)
Think of mechanical energy as a financial budget. The money can be in your wallet (kinetic), in your savings account (gravitational potential), or locked in an investment (elastic potential) — but the total amount of money you own hasn't changed.