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Posts tagged “power”

By Robert Rapier on Feb 6, 2012 with 41 responses

Confused about Energy and Power?

When I recently solicited feedback for topics to cover for my upcoming book, several people requested that I discuss the difference between energy and power. Just two weeks ago Congressman Dana Rohrabacher, R-Calif., who is on the House Committee on Science, Space, and Technology, admitted that he’s “not educated enough to know the difference between the terms … energy and power.” You would certainly expect that someone who influences legislation over science and technology would know the difference, but it is true that people commonly get confused between the two.

So this weekend I wrote up a sidebar for Power Plays discussing the differences, which I share below. If you believe that a point could be clearer, or if anything about my explanation is confusing, I would be happy to hear reader feedback.

Energy, Power, and Units of Measurement

There are a number of potentially confusing units of measurement for energy and power. The first thing to understand, however, is the difference between energy and power. Technically speaking, energy refers to the capacity of a system to do work. In this definition, “a system” could be a gallon of gasoline that contains 115,000 British Thermal Units (BTUs) – a unit of energy. In addition to the BTU, some other units of energy are the joule (J), the calorie (cal), and the watt hour (Wh). Multiples of these units have abbreviations like kilo (one thousand) or mega (one million), so one kilowatt hour (kWh) is one thousand watt hours. Each of these units can be converted into the other. One BTU is equal to 1,055 joules, 252 calories, or 0.29 watt hours.

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