How is energy defined and measured?
Overview of how scientists use the joule unit to measure work or energy.
Encyclopædia Britannica, Inc.
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© MinutePhysics (A Britannica Publishing Partner)Learn about antimatter and its properties.
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Encyclopædia Britannica, Inc.How energy can change from one form to another. Examples presented include a lightbulb, a car's engine, and plant photosynthesis.
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© World Science Festival (A Britannica Publishing Partner)When matter meets antimatter, the particles annihilate each other. So, in our evolving universe, why is there any matter left over? Brian Greene discusses developments in the study of neutrino asymmetry. This video is an episode in his Daily Equation series.
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Encyclopædia Britannica, Inc.Explanation of the principle of the conservation of energy.
Transcript
What is energy, and how do we measure it?
One way to define energy is the ability to do work, where work equals force, measured in newtons, times the distance, measured in meters, an object is moved in the direction of the force.
Scientists use the joule to measure work. One joule is equal to the work done by a force of one newton to move an object one meter in the direction of the force.
To use a real-life example, gravity exerts about 1 newton of force on the average apple.
To raise an apple one meter in the air, you must use one joule of kinetic energy.
The apple held one meter up has a potential energy of 1 joule.
Now it has none!
One way to define energy is the ability to do work, where work equals force, measured in newtons, times the distance, measured in meters, an object is moved in the direction of the force.
Scientists use the joule to measure work. One joule is equal to the work done by a force of one newton to move an object one meter in the direction of the force.
To use a real-life example, gravity exerts about 1 newton of force on the average apple.
To raise an apple one meter in the air, you must use one joule of kinetic energy.
The apple held one meter up has a potential energy of 1 joule.
Now it has none!