Conservation of Energy

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Law of Conservation of Energy Noun

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[law uv kon-ser-vay-shun uv en-er-jee]

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Law of Conservation of Energy

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The principle that energy cannot be created or destroyed in an isolated system, only changed from one form to another.

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Example: A swinging pendulum shows energy transforming from potential energy (at the highest point) to kinetic energy (at the lowest point), but the total energy is conserved.

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Closed System Noun

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[klohzd sis-tuhm]

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Closed System

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A physical system that does not exchange matter with its surroundings, though it may exchange energy with them.

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Example: This diagram shows a closed system can exchange energy (red arrow) with its surroundings, but not matter, unlike open or isolated systems.

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Isolated System Noun

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[ay-suh-ley-tid sis-tuhm]

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Isolated System

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A physical system so far removed from other systems that it does not interact with them, conserving total energy.

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Example: The Earth-Moon system is considered isolated because, with no external forces, its total energy is conserved as the Moon orbits Earth.

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Mechanical Energy Noun

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[muh-kan-i-kuhl en-er-jee]

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Mechanical Energy

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The sum of potential energy and kinetic energy, representing the energy associated with an object's motion and position.

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Example: A roller coaster demonstrates mechanical energy, which is the sum of potential energy (stored energy of position) and kinetic energy (energy of motion).

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Gravitational Potential Energy Noun

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[grav-i-tey-shuh-nl puh-ten-shuhl en-er-jee]

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Gravitational Potential Energy

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The energy an object possesses because of its position in a gravitational field, relative to some reference point.

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Example: A figure standing at the top of stairs has stored energy (gravitational potential energy) because of its high position, ready to be converted into motion.

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Elastic Potential Energy Noun

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[ih-las-tik puh-ten-shuhl en-er-jee]

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Elastic Potential Energy

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The potential energy stored as a result of the deformation of an elastic object, such as stretching a spring.

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Example: Stretching a spring by applying a force stores energy in it; this stored energy is called elastic potential energy.

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Translational Kinetic Energy Noun

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[trans-ley-shuh-nl ki-net-ik en-er-jee]

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Translational Kinetic Energy

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The energy of an object due to its motion from one location to another, as opposed to rotational motion.

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Example: This image shows the mathematical formula for translational kinetic energy, defining it as half the mass of an object multiplied by its speed squared.

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Rotational Kinetic Energy Noun

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[roh-tey-shuh-nl ki-net-ik en-er-jee]

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Rotational Kinetic Energy

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The kinetic energy of an object due to its rotation or spinning motion around an axis.

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Example: This diagram shows a steam turbine. The force of the steam pushes on the blades, causing the entire turbine to spin, giving it rotational kinetic energy.

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Conservation of Mechanical Energy Noun

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[kon-ser-vay-shun uv muh-kan-i-kuhl en-er-jee]

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Conservation of Mechanical Energy

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The principle that the total mechanical energy in an isolated system remains constant if only conservative forces are acting.

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Example: A pendulum swings, converting potential energy at its highest point to kinetic energy at its lowest point, keeping the total mechanical energy constant.

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Thermal Energy Noun

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[thur-muhl en-er-jee]

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Thermal Energy

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The internal energy of an object due to the kinetic energy of its atoms and molecules, often produced by friction.

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Example: This diagram shows that thermal energy flows as heat from a hot object (red block) to a colder object (blue block).