Suppose 2 r satises r2 r2 r cos then r r 2

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Unformatted text preview: ow the equilibrium position with an upward velocity of 8 feet per second, find the equation of motion of the object, x(t). What is the longest distance the object travels above the equilibrium position? When does this first happen? Confirm your result using a graphing utility. Solution. In order to use the formulas in Theorem 11.1, we first need to determine the spring constant k and the mass of the object m. To find k , we use Hooke’s Law F = kd. We know the object weighs 64 lbs. and stretches the spring 8 ft.. Using F = 64 and d = 8, we get 64 = k · 8, or k = 8 lbs. . To find m, we use w = mg with w = 64 lbs. and g = 32 ft. . We get m = 2 slugs. We can ft. s2 now proceed to apply Theorem 11.1. k 1. With k = 8 and m = 2, we get ω = m = 8 = 2. We are told that the object is released 2 3 feet below the equilibrium position ‘from rest.’ This means x0 = 3 and v0 = 0. Therefore, √ 2 A= x 2 + v0 = 32 + 02 = 3. To determine the phase φ, we have A sin(φ) = x0 , 0 ω 13 The sign convention...
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This note was uploaded on 05/03/2013 for the course MATH Algebra taught by Professor Wong during the Fall '13 term at Chicago Academy High School.

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