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Life is full of surprises: our approximate condition for the fall of a body through a resisting medium is precisely analogous to the exact condition … - George Pólya
" "Life is full of surprises: our approximate condition for the fall of a body through a resisting medium is precisely analogous to the exact condition for the flow of an electric current through a resisting wire [of an induction coil<nowiki>]</nowiki>. ...
<math>m\frac {dv}{dt} = mg - Kv</math>
This is the form most convenient for making an analogy with the "fall", i.e., flow, of an electric current.
...in order from left to right, mass <math>m</math>, rate of change of velocity <math>\frac {dv}{dt}</math>, gravitational force <math>mg</math>, and velocity <math>v</math>. What are the electrical counterparts? ...To press the switch, to allow current to start flowing is the analogue of opening the fingers, to allow the body to start falling. The fall of the body is caused by the force <math>mg</math> due to gravity; the flow of the current is caused by the electromotive force or tension <math>E</math> due to the battery. The falling body has to overcome the frictional resistance of the air; the flowing current has to overcome the electrical resistance of the wire. Air resistance is proportional to the body's velocity <math>v</math>; electrical resistance is proportional to the current <math>i</math>. And consequently rate of change of velocity <math>\frac {dv}{dt}</math> corresponds to rate of change of current <math>\frac {di}{dt}</math>. ...The electromagnetic induction <math>L</math> opposes the change of current... And doesn't the inertia or mass <math>m</math>..? Isn't <math>L</math>, so to speak, an electromagnetic inertia?
<math>L\frac {di}{dt} = E - Ki</math>
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About George Pólya
George Pólya (December 13, 1887 – September 7, 1985) was a Hungarian mathematician and professor of mathematics at ETH Zürich and at Stanford University. His work on heuristics and pedagogy has had substantial and lasting influence on mathematical education, and has also been influential in artificial intelligence.
Biography information from Wikiquote
Also Known As
Native Name:
Pólya György
Alternative Names:
George Polya
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Georg Polya
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Georg Pólya
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Additional quotes by George Pólya
<math>\frac {dy}{dx} = \frac {\omega^2x}{g}</math>...The first derivative, the result of the differentiation of <math>y</math> with respect to <math>x</math>, was written by Leibniz in the form
<math>\frac {dy}{dx}</math>...Leibniz's notation ...is both extremely useful and dangerous. Today, as the concepts of limit and derivative are sufficiently clarified, the use of the notation... need not be dangerous. Yet, the situation was different in the 150 years between the discovery of calculus by Newton and Leibniz and the time of Cauchy. The derivative <math>\frac {dy}{dx}</math> was considered as the ratio of two "infinitely small quanitites", of the infinitesimals <math>dy</math> and <math>dx</math>. ...it greatly facilitated the systematization of the rules of the calculus and gave intuitive meaning to its formulas. Yet this consideration was also obscure... it brought mathematics into disrepute... some of the best minds... such as... Berkeley, complained that calculus is incomprehensible. ...<math>\frac {dy}{dx}</math> is the limit of a ratio of <math>dy</math> to <math>dx</math>... Once we have realized this sufficiently clearly, we may, under certain circumstances, treat <math>\frac {dy}{dx}</math> so as if it were a ratio... and multiply by <math>dx</math> to achieve the separation of variables. We get
<math>{dy} = \frac {\omega^2x}{g}xdx</math>
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