* Potential Energy: Energy stored due to an object's position or configuration. Think of a ball held high in the air.
* Kinetic Energy: Energy of motion. The same ball falling towards the ground.
* Mechanical Energy: The sum of potential and kinetic energy.
The Key: In a closed system, where only conservative forces (like gravity) are acting, the total mechanical energy remains constant. This means that as potential energy decreases, kinetic energy increases by the same amount, and vice versa.
Examples:
* A Roller Coaster: As the roller coaster climbs a hill, it gains potential energy and loses kinetic energy (slowing down). When it descends, it loses potential energy and gains kinetic energy (speeding up). The total mechanical energy remains the same.
* A Pendulum: At the highest point of its swing, the pendulum has maximum potential energy and zero kinetic energy. At the bottom of the swing, it has maximum kinetic energy and zero potential energy. Throughout its motion, the total mechanical energy is conserved.
Important Note: This principle applies in situations where non-conservative forces (like friction) are negligible. Friction converts mechanical energy into heat, reducing the total mechanical energy.
