# lecture23 - Physics 1D03 Lecture 24 Energy Serway 8.4-8.6...

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Unformatted text preview: Physics 1D03 - Lecture 24 Energy Serway 8.4-8.6; 10.8 • Examples with rotation • Force and Potential Energy Physics 1D03 - Lecture 24 Mechanical Energy E = K + U = K + U gravity + U spring + ... Mechanical energy is conserved by “conservative” forces; the total mechanical energy does not change if only conservative forces do work. Remember, for a conservative system: ΔK+ΔU=0 Physics 1D03 - Lecture 24 Non-Conservative Forces Non-conservative forces cause the mechanical energy of the system to change. Divide work W into work by conservative forces and work by “other” forces.: ∆ K = W = W c + W other W c can be replaced by potential energy terms: W c = - ∆ U , so ∆ K = - ∆ U + W other and, since E=K+U , ∆ E = W other The change in mechanical energy is equal to the work by “other” forces. “Other” means any force not represented by a term in the potential energy. It includes non-conservative forces, but also externally-applied forces, conservative or not, that transfer energy into or out of the system. Physics 1D03 - Lecture 24 Conservation of Energy Other types of energy:- electrostatic P.E.- chemical P.E.- nuclear P.E.- etc., etc., and thermal energy (actually just kinetic and potential energy at a microscopic scale) Then: The total energy of the universe is conserved. Physics 1D03 - Lecture 24...
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## This note was uploaded on 11/08/2010 for the course PHYSICS PHYSICS 1D taught by Professor Mckay during the Spring '09 term at McMaster University.

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lecture23 - Physics 1D03 Lecture 24 Energy Serway 8.4-8.6...

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