if perpetual motion is impossible, why/how do planets orbit and spin continually?
In: Physics
When people say “perpetual motion is impossible” they are using the term “perpetual motion” improperly: what they really mean is that overunity motion is impossible. What is overunity, you may ask. I’ll explain.
Any moving object has a reserve of energy. Let’s assume that it equals 100% at the beginning. Part of this energy is spent to contrast friction, so that the object can remain in motion. Take away the friction part, and you remain with… let’s say 60% energy you can use for yourself. But energy needs to be converted (typically to electricity), and every conversion generates heat as a side effect, which is more energy that is dispersed into the environment and you cannot use. Let’s say this is a further 30%, so you end up with only being able to use the remaining 30% of the original energy.
Pretty simple, right? Well, apparently, for some people this is too complicated, or they are in denial about how the universe works. Other people know very well how the universe works, but intentionally spread misinformation in order to make profit (by persuading people to buy machines they know won’t work). According to these people, if you start with 100% of energy, you can take out some of it for your purposes (let’s say 30% again), and at the same time you supposedly can give THE WHOLE 100% of the energy back to the object. This (if it was possible, which is NOT) would mean that you started with 100% (a “unit”), but you ended up with 130% (OVER a UNIT, overunity).
Of course, if you ask this kind of people (I call them “perpetuists”) where the additional energy comes from, they either fall in contradiction and/or recur to hazy description that don’t really explain anything, so you know what they’re up to.
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