MCQOPTIONS
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MCQOPTIONS
This section includes 7 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Vibrations knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A concentrated mass m is attached at the center of a rod of length 2 L as shown in figure. The rod is kept in a horizontal equilibrium position by a spring of stiffness 4 k. For very small amplitude of vibration, neglecting the weight of the rod and spring, the undamped natural frequency (wn) of the system is |
| A. | \(\sqrt {\frac{{2k}}{m}} \) |
| B. | \(\sqrt {\frac{{4k}}{m}} \) |
| C. | \(\sqrt {\frac{{8k}}{m}} \) |
| D. | \(\sqrt {\frac{{16k}}{m}} \) |
| Answer» E. | |
| 2. |
In a single degree of freedom underdamped spring-mass-damper system as shown in the figure, an additional damper is added in parallel such that the system remains underdamped. Which one of the following statements is ALWAYS true? |
| A. | Transmissibility will increase. |
| B. | Transmissibility will decrease. |
| C. | Time period of free oscillations will increase. |
| D. | Time period of free oscillations will decrease. |
| Answer» D. Time period of free oscillations will decrease. | |
| 3. |
Consider a two degree of freedom system as shown in the figure, where PQ is a rigid uniform rod of length, b and mass m.Assume that the spring deflects only horizontally and force F is applied horizontally at Q. For this system, the Lagrangian, L is |
| A. | \( \frac{1}{2}\left( {M + m} \right){\dot x^2} + \frac{1}{2}mb\dot \theta \dot x\cos \theta + \frac{1}{6}m{b^2}{\dot \theta ^2} - \frac{1}{2}k{x^2} + mg\frac{b}{2}\cos \theta \) |
| B. | \(\frac{1}{2}m{\dot x^2} + \frac{1}{2}mb\dot \theta \dot x\cos \theta + \frac{1}{6}m{b^2}{\dot \theta ^2} - \frac{1}{2}k{x^2} + mg\frac{b}{2}\cos \theta + fb\sin \theta \) |
| C. | \(\frac{1}{2}m{\dot x^2} + \frac{1}{2}mb\dot \theta \dot x\cos \theta + \frac{1}{6}m{b^2}{\dot \theta ^2} - \frac{1}{2}k{x^2} \) |
| D. | \( \frac{1}{2}\left( {M + m} \right){\dot x^2} + \frac{1}{2}mb^2\dot \theta^2 - \frac{1}{2}k{x^2} + mg\frac{b}{2}\cos \theta \) |
| Answer» B. \(\frac{1}{2}m{\dot x^2} + \frac{1}{2}mb\dot \theta \dot x\cos \theta + \frac{1}{6}m{b^2}{\dot \theta ^2} - \frac{1}{2}k{x^2} + mg\frac{b}{2}\cos \theta + fb\sin \theta \) | |
| 4. |
A refrigerator unit having a mass of 35 kg is to be supported on three springs, each having spring stiffness. The unit operates at 480 rpm. If only 10% of the shaking force is allowed to transmit to the supporting structure, the value of stiffness will be nearly |
| A. | 2.7 N/mm |
| B. | 3.2 N/mm |
| C. | 3.7 N/mm |
| D. | 4.2 N/mm |
| Answer» B. 3.2 N/mm | |
| 5. |
A periodic is represented by x(t) = sin (50t - \(\frac{\pi }{3}\)), where distance is measured in mm, phase angle in radians and time in seconds. Time period of this motion, in seconds is: |
| A. | \(\frac{\pi }{{50}}\) |
| B. | \(\frac{\pi}{25}\) |
| C. | \(\frac{\pi}{15}\) |
| D. | \(\frac{\pi}{10}\) |
| Answer» C. \(\frac{\pi}{15}\) | |
| 6. |
A vibrometer |
| A. | Indicates vibration amplitude |
| B. | Indicates vibration frequency |
| C. | Indicates mature of vibrations |
| D. | Only indicates second and above harmonics |
| Answer» B. Indicates vibration frequency | |
| 7. |
Dynamically unbalanced masses in rotating machines cause |
| A. | vibration |
| B. | noise |
| C. | friction |
| D. | wear |
| Answer» B. noise | |