PHY293 Oscillations Lecture #3 September 15, 2009 1. Tutorials start Thursday 2. First problem set is now posted ( http://www.physics.utoronto.ca/ phy293h1f/waves/phy293 ps1.pdf ) 3. There was a small clariﬁcation/addition to problem 3 after the ﬁrst posting Start of material 1. Damped Simple Harmonic Motion • Perpetual motion machines do not exist because of damping • Energy juggling cannot go on forever • Resistance, friction, dissipation is always present ◦ We only know about oscillating systems because of dissipative phenomena ◦ Hearing a tuning fork ⇒ vibrations transmitted to air ◦ Observe LC oscillation ⇒ voltage dropped across a resistor ◦ Feel waves ⇒ because of the viscosity of the medium they are moving in • Dissipation proportional to ˙ x (velocity) ◦ Microscopically there is no dissipation ◦ Dissipation comes from increased randomness, averaged over a system gives the overall damping ◦ eg. Heat is generated by increased randomness, averaged over whole system that gets hot)
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This note was uploaded on 07/10/2011 for the course PHY 293 taught by Professor Pierresavaria during the Fall '07 term at University of Toronto.