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How to calculate Joules

Let's go over some of the examples Adabot and Mr. Joule use in the video.  In order to calculate Joules, we can use one of two simple equations.  The first one uses measurements of force in newtons and distance in meters

Mr. Joule uses a force of 1 newton to lift an apple 1 meter.  Therefore …

1 newton x 1 meter = 1 joule

and in order to lift 40 apples, he uses a force of 40 newtons …

40 newtons x 1 meter = 40 joules 

The second equation we can use to calculate Joules uses measurements of Power in watts and time in seconds …

Mr. Joule explains that if we light a 3 watt LED for 3 seconds we've used 9 joules of work:

3 watts x 3 seconds = 9 joules

and if we light a 60 watt incandescent bulb for one hour:

1 hour = 3600 seconds

60 watts x 3600 seconds = 216,000 joules

and a more efficient LED light bulb which uses 12 watts could use less work to provide just as much light:

12 watts x 3600 seconds = 43,200 joules

If you know power & time, or force & distance - calculating joules is quite simple!


James Prescott Joule

from Wikipedia

James Prescott Joule was an English physicist and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work. This led to the law of conservation of energy, which led to the development of the first law of thermodynamics. The SI derived unit of energy, the joule, is named after James Joule. He worked with Lord Kelvin to develop the absolute scale of temperature the kelvin. Joule also made observations of magnetostriction, and he found the relationship between the current through a resistor and the heat dissipated, which is now called Joule's first law.

learn more about Mr. Joule

This guide was first published on Aug 26, 2016. It was last updated on Aug 26, 2016. This page (Learn More) was last updated on Jun 01, 2019.