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प्रश्न
What do you understand by free (or natural) vibrations?
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उत्तर
Any object when slightly disturbed from its position of rest or equilibrium vibrates with its own period irrespective of its size or shape, is said to make vibrations. The time period of said vibrations is called natural time period and the frequency is called natural frequency. In the absence of any resistance such as air, the amplitude of free vibration remains constant.
संबंधित प्रश्न
A tuning fork of frequency 256 Hz will resonate with another tuning fork of frequency:
In fig. , P, Q, R and S represent test tubes each of height 20 cm which are filled with water upto heights of 10 cm, 14 cm, 16 cm and 18 cm respectively. If a vibrating tuning fork is placed over the mouth of test tube Q, a loud sound is heard.
(i) Describe the observations with the tubes P, R and S.
(ii) Give the reason for your observation in each case.
(iii) State the principle illustrated by the above experiment.
In Fig. A, B, C and D are four pendulums suspended from the same elastic string XY. The lengths of pendulum A and D are equal, while the length of pendulum B is shorter and of the pendulum C is longer. Pendulum A is set into vibrations.
- What is your observation about the vibrations of pendulum D?
- Give reason for your observation in part (a).
- What type of vibrations take place in pendulums Band C?
- Give reason for the answer in part (c).
The diagram below shows three different modes of vibration P, Q and R of the same string of a given length.
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| P | Q | R |
- Which vibration will produce a louder sound and why?
- Which vibration will produce sound of maximum shrillness (or pitch) and why?
- What is the ratio of wavelength of vibrations P and R?
When acoustic resonance takes place, a loud sound is heard. Why does this happen? Explain.
State two ways in which resonance differs from forced vibrations.
The rearview mirror of a motorbike starts vibrating violently at some particular speed of the motorbike. What is the name of the phenomenon taking place? Why does the happen?
A vibrating tuning fork is placed over the mouth of a burette filled with water. The tap is opened and the water level gradually falls. It is observed that the sound becomes the loudest for a particular length of the air column. What is the name of the phenomenon taking place when this happens? Why does the sound become the loudest?
What do you understand by forced vibrations?
What do you understand by free vibrations of a body? Draw a displacement-time graph to represent them. Given one example.
