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Chapter 13: S.H.M. Simple harmonic motion is the projection of uniform circular motion on a diameter. . dx. dt. d 2 x. dt 2. dv. dt. x = A Cos(t + ). v = = - A Sin(t + ). 2. = = 2 f. T. a = = = - 2 A Cos(t + ). mg. mg. L. L.
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Simple harmonic motion is the projection of uniform circular motion on a diameter.
dx dt d2x dt2 dv dt x = A Cos(t + ) v = = - A Sin(t + ) 2 = = 2 f T a = = = - 2 A Cos(t + )
mg mg L L F = -mg Sin -mg x = L F - x F = -kx k = = max Cos(t + ) g k = = m L
d2x dx m + b + kx = 0 dt2 dt b = 2m k b2 `= - m 4m2 k b2 ` 1 - f = = m 4m2 2 2 t Fdamping = -bv ma = -kx - bv Guess the Solution x = Ae-t Cos(`t) A : Underdamped B : Critical Damping C : Overdamping b2 << 4mk b2 = 4mk b2 > 4mk