Advertisements
Advertisements
Question
Differentiate between the following:
Free and forced vibrations.
Advertisements
Solution
| Free vibrations | Farced vibrations |
| 1. When a body vibrates with its natural frequency and ti me period which is characteristic of the body itself, it is said to have free vibrations. | 1. When a body is set into vibrations with the help of a strong periodic force then the vibration is said to be forced vibration. The frequency of such vibrations may not be equal to the natural frequency of the body. |
| 2. It is difficult to realize such vibrations in practice. They can take place only in vacuum. | 2. Such vibrations can be realized in practice. |
APPEARS IN
RELATED QUESTIONS
The adjacent diagram shows three different modes of vibrations P, Q and R of the same string.
(i) Which vibration will produce a louder sound and why?
(ii) The sound of which string will have maximum shrillness?
(iii) State the ratio of wavelengths of P and R.
The diagram above shows a wire stretched over a sonometer. Stems of two vibrating tuning forks A and Bare touched to the wooden box of the sonometer. It is observed that the paper rider (a small piece of paper folded at the centre) present on the wire flies off when the stem of vibrating tuning fork B is touched to the wooden box but the paper just vibrates when the stem of vibrating tuning fork A is touched to the wooden box.
1) Name the phenomenon when the paper rider just vibrates.
2) Name the phenomenon when the paper rider flies off.
3) Why does the paper rider fly off when the stem of tuning fork B is touched to the box?
Why is a loud sound heard at resonance?
In following figure shows A, B , C and D represent test tube each of height 20 cm which are filled with water up to heights of 12 cm, 14 cm, 16cm and 18cm respectively. If a vibrating tuning fork is placed over the mouth if test tube D, a loud sound is heard.
- Describe the observations with the tubes A, B and C when the vibrating tuning fork is placed over the mouth of these tubes.
- Give the reason for your observation in each case.
- 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 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?
The rearview mirror of a motorbike starts vibrating violently at some particular speed of the motorbike, what could be done to stop the violent vibrations.
Explain Why are stringed musical instruments provided with large sound boxes?
What are the factors that affect the frequency of a vibrating string and how do they affect the frequency?
Explain free and forced vibrations. Give an experimental arrangement to illustrate the phenomenon of resonance.
