Page 117 - Singiresu S. Rao-Mechanical Vibrations in SI Units, Global Edition-Pearson (2017)

114 Chapter 1 Fundamentals oF Vibration
10. Continuous or distributed systems can be considered to have number of degrees
of freedom.
11. Systems with a finite number of degrees of freedom are called systems.
12. The number of degrees of freedom of a system denotes the minimum number of inde-
pendent necessary to describe the positions of all parts of the system at any instant
of time.
13. If a system vibrates due to initial disturbance only, it is called vibration.
14. If a system vibrates due to an external excitation, it is called vibration.
15. Resonance denotes the coincidence of the frequency of external excitation with a(n)
frequency of the system.
16. A function f(t) is called an odd function if .
17. The range expansions can be used to represent functions defined only in the inter-
val 0 to t.
18. analysis deals with the Fourier series representation of periodic functions.
19. The rotational speed of 1000 rpm (revolutions per minute) is equivalent to _____
radians/s.
20. When the speed of a turbine is 6000 rpm, it takes seconds for the turbine to
complete one revolution.

1.4 Select the most appropriate answer from the multiple choices given:

1. The world’s first seismograph was invented in
(a) Japan (b) China (c) Egypt
2. The first experiments on simple pendulums were conducted by
(a) Galileo (b) Pythagoras (c) Aristotle
3. The Philosophiae Naturalis Principia Mathematica was published by
(a) Galileo (b) Pythagoras (c) Newton
4. Mode shapes of plates, by placing sand on vibrating plates, were first observed by
(a) Chladni (b) D’Alembert (c) Galileo
5. The thick beam theory was first presented by
(a) Mindlin (b) Einstein (c) Timoshenko
6. The number of degrees of freedom of a simple pendulum is:
(a) 0 (b) 1 (c) 2
7. Vibration can be classified in
(a) one way (b) two ways (c) several ways
8. Gibbs’ phenomenon denotes an anomalous behavior in the Fourier series representation of a
(a) harmonic function (b) periodic function (c) random function
9. The graphical representation of the amplitudes and phase angles of the various frequency
components of a periodic function is known as a
(a) spectral diagram (b) frequency diagram (c) harmonic diagram
10. When a system vibrates in a fluid medium, the damping is
(a) viscous (b) Coulomb (c) solid
11. When parts of a vibrating system slide on a dry surface, the damping is
(a) viscous (b) Coulomb (c) solid
12. When the stress-strain curve of the material of a vibrating system exhibits a hysteresis
loop, the damping is
(a) viscous (b) Coulomb (c) solid