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THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

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616 20. Vibration and Vibration ControlProblems for Chapter 201. In the spring-dashpot system of Figure 20.1, weight W = 50 N, spring constantk = 0.30 N/cm, and damping ratio ξ = 0.35. Find the natural frequency andthe viscous damping of the system.2. Establish the characteristic equation for the spring-dashpot system ofProblem 1 and determine the additional viscous damping needed to yielda critically damped system.3. In the system of Problem 1, the mass is displaced 15 cm and then suddenlyreleased. Set up the equation for the system response, which describes theposition of the mass as a function of time.4. Consider a spring-dashpot system that has the following parameters: W =40 N, C = 0, and k = 0.39 N/cm. If the mass is initially displaced and released,how will the system response?5. In a spring-dashpot system, W = 40 N, C = 0.10 N/cm/s, and a forcing function4.0 sin ω n t drives the system. What kind of system response will occuras a function of time?6. In a spring-damper system of Figure 20.1, W = 250 N, C = 0.13 N/cm/s,and k = 32 N/cm. How much does the spring deflect under the dead weightload of the mass? What is the natural frequency of the system? If the systemundergoes a forced harmonic oscillation described by F = F 0 sin 12t, whichone of the system parameters effectively controls the response of the system?7. A mass is supported by four identical springs, each having a spring constantof 2.6 N/cm. If the spring deflects 1.5 cm, what is the weight of the mass beingsupported?8. Consider the system described in the last problem. It is forced with a sinusoidalsignal with a frequency twice that of its natural frequency. Find the degree ofvibration isolation that will be obtained.9. A mechanical system is being designed for installation in a plant. It bearsthe following parameters: W = 2000 N and k = 3.65 N/cm. If the forcingfrequency = 12 rad/s, how much damping can the system tolerate if the isolationmust exceed 90%?10. In a spacecreaft, delicate electronic sensors have to be isolated from a panelthat vibrates at 50 rad/s. It is required that at least 90% vibration isolationcan be achieved by using springs to protect the equipment. Assume that thedamping ratio ξ = 0. What static deflection is required?

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