The Many Forms of Energy

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Energy Noun

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[en-er-jee]

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Energy

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The ability of a system to produce a change in itself or the world around it; the capacity for doing work.

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Example: This diagram shows how stored potential energy in a ball held high is converted into kinetic energy, the energy of motion, as it falls.

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Kinetic Energy Noun

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[ki-net-ik en-er-jee]

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Kinetic Energy

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The energy that an object or a system's components possess due to their motion.

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Example: A marble rolling down a track possesses kinetic energy because it is in motion. The arrows show the path of this energy of movement.

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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 an object possesses due to its linear motion from one location to another.

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Example: This image shows three examples of translational kinetic energy: a swinging pendulum, a moving bicyclist, and a hiking person, all demonstrating energy of motion.

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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 an object possesses due to its rotational motion around an internal axis.

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Example: The spinning Earth has rotational kinetic energy because it is a massive object in motion, rotating around its axis.

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Moment of Inertia Noun

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[moh-muhnt uhv in-ur-shuh]

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Moment of Inertia

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A quantity that measures a body's resistance to angular acceleration, analogous to mass in linear motion.

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Example: Applying a force to a bike wheel causes it to spin (angular acceleration). The wheel's moment of inertia is its resistance to this change in rotation.

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Angular Velocity Noun

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[ang-gyuh-ler vuh-los-i-tee]

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Angular Velocity

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The rate of change of angular displacement, specifying the rotational speed and direction of an object.

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Example: A fluid pushes the turbine blades, causing the central shaft to rotate. Angular velocity measures how fast an object spins, like this turbine shaft.

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Potential Energy Noun

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[puh-ten-shuhl en-er-jee]

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Potential Energy

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Stored energy held by an object or system due to its position, arrangement, or internal state.

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Example: A box gains gravitational potential energy when it is lifted to a certain height above the ground, storing energy due to its position.

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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 stored energy an object possesses due to its position within a gravitational field, relative to a reference point.

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Example: This diagram shows that an object's gravitational potential energy depends on its mass (m), its height (h) above a surface, and the acceleration due to gravity (g).

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Reference Level Noun

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[ref-er-uhns lev-uhl]

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Reference Level

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The arbitrary position or height where the gravitational potential energy of a system is defined as being zero.

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Example: This diagram shows that the 'reference level' is the zero point from which an object's height (h) is measured, which is necessary to calculate its gravitational potential energy.

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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 in an elastic object as a result of its deformation, like stretching or compressing.

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Example: This diagram shows that when a spring is compressed or stretched away from its static state, it stores elastic potential energy.