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	Podcast:		4. Chemistry and Physics
	Episode:		Thermal Energy
	Category:		Science & Medicine
	Duration:		00:01:23
	Publish Date:		2011-07-13 19:48:34
	Description:		Transcript: Heat sometimes seems like a fluid. We talk about heat flowing from one place to another, objects giving off heat, or absorbing heat. Heat is actually a measure of the random disordered motion of microscopic atoms and molecules in a substance. The larger the microscopic random motions, the more the heat. This is called thermal energy, or heat energy, and as in all other forms of energy it is measured in units of joules. The fact that heat can be quantified and is truly a form of energy was shown by James Prescott Joule. In 1840 he did an elegant experiment where he arranged for a falling weight to rotate a paddle in a column of water. The rotating paddle stirred the water up and was able to heat it measurably with a thermometer. Joule deduced that a one pound weight falling through the equivalent of 770 feet was able to heat a specific amount of water by one degree Fahrenheit, thus demonstrating that the gravitational potential energy of the falling weight was being turned into the kinetic energy of the paddle’s motion and then into increased microscopic motions of the molecules of water.
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