Perpetual Motion

Topics: Entropy, Second law of thermodynamics, Conservation of energy Pages: 3 (873 words) Published: November 12, 2008
Perpetual Motion

I will be researching perpetual motion and why it is said to be impossible. The reason I chose this topic is because I remember learning the laws of thermodynamics in my eighth grade science class. After explaining these laws, the teacher added, “…and that is why perpetual motion machines are impossible.” Since we have been studying related topics such as motion, gravity, and friction, I figure it would be a great time to learn specifically why it is considered impossible for perpetual motion machines to work.

Perpetual motion is the action of a moving device that requires no input of energy to maintain it, and therefore can continue forever. However the term perpetual motion is perhaps a bit misleading, since technically, nothing about the laws of thermodynamics prohibits something from moving forever. Arguably, the motion of planets in space and electrons in atoms is, in some sense, perpetual. But the point of building a perpetual motion machine is typically not just to get something to stay in motion, but to do work of some sort, such as: propel a vehicle, power a mill, heat your coffee, or run your computer. Any output of energy (whether in the form of heat, electricity, or motion) that goes beyond the input minus what the machine itself uses is what conflicts with the laws of thermodynamics. Nowadays, designers are concerned less with producing motion than with producing excess energy in the form of electricity of heat, so terms such as “free energy” and “over-unity” are often applied to devices, moving or not, whose energy output supposedly exceeds their input.

The First Law of Thermodynamics, also known as the Law of Conservation of Energy, states that energy can be neither created nor destroyed. Thus, the total energy within a system is a constant, although a system can turn one form of energy into another, the net output can never be greater than the input. The Second Law of Thermodynamics, also known as the Law of...
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