In Problems 1 through 6, express the solution of the given initial value problem as a sum of two oscillations as in Eq. (8). Throughout, primes denote derivatives with respect to time t. In Problems 14, graph the solution function x.t / in such a way that you can identify and label (as in Fig. 3.6.2) its period.
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Textbook Solutions for Differential Equations and Boundary Value Problems: Computing and Modeling
Question
A mass m hangs on the end of a cord around a pulley of radius a and moment of inertia I, as shown in Fig. 3.6.11. The rim of the pulley is attached to a spring (with constant k). Assume small oscillations so that the spring remains essentially horizontal and neglect friction. Find the natural circular frequency of the system in terms of m, a, k, I , and g.
Solution
Step 1 of 3
Let m be the mass that hangs to the cord of the pulley with radius a and inertia I. Let x be the displacement of the mass from its equilibrium position.
Then v = x’ be its velocity, and \({\omega _0} = v/a\) be the angular velocity of the pulley.
The objective is to find the natural frequency of the system.
As the rim of the pulley is attached to the spring, the conservation of energy of the system yields:
\(\frac{1}{2}m{v^2} + \frac{1}{2}I\omega _0^2 + \frac{1}{2}k{x^2} - mgx = C\)
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