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This lecture covers the application of derivative rules in electric circuits, including voltage, current, and power. It also discusses the use of derivatives in analyzing the behavior of beams under different loads and their deflection.
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EGR 1101: Unit 9Lecture #1 Applications of Derivatives: Electric Circuits (Section 8.4 of Rattan/Klingbeil text)
Review: Some Derivative Rules where a, c, n, and are constants.
Two New Derivative Rules • (Product rule) • If f(g) is a function of g and g(t) is a function of t, (Chain rule)
Today’s Examples • Voltage, current, & power • Current & voltage in an inductor • Current & voltage in an inductor (graphical and working backwards) • Current & voltage in a capacitor • Current & voltage in a capacitor (graphical and working backwards)
Voltage-versus-Current Relations • For resistors, • For inductors, • For capacitors,
EGR 1101: Unit 9Lecture #2 Applications of Derivatives: Beams (Section 8.5 of Rattan/Klingbeil text)
Some Beam Terminology • Types of beams • Simply supported • Cantilever • Types of load on a beam • Concentrated • Distributed
More Beam Terminology • In addition to the type of beam and load, a beam’s behavior also depends on its geometry and the material it is made of. • Its geometry is summarized in a quantity called the second moment of area (I). • Its material is summarized in a quantity called the modulus of elasticity (E). • The product of these two (EI) is called the flexural rigidity.
Excellent Online Resource • University of Wisconsin’s online lessons on Strength of Materials: http://www3.uwstout.edu/faculty/scotta/upload/Foley-StaticsStrengths.pdf • See especially Topic 4 (Beams) and Topic 8.2 (Stress on Incline Planes).
Review • Given a function f(x), the function’s local maxima occur at values of x where and • Its local minima occur at values of x where and
Today’s Examples • Deflection of a cantilever beam with end load • Deflection of a simply supported beam with central load • Deflection of a simply supported beam with distributed load • Maximum stress under axial loading