Physics
The diagram in figure below shows the displacement-time graph of a vibrating body.
(i) Name the kind of vibrations.
(ii) Give one example of such vibration.
(iii) Why is the amplitude of vibrations gradually decreasing?
(iv) What happens to the vibrations of the body after some time?
Answer
(i) The above shown displacement-time graph of a vibrating body represents damped vibrations.
(ii) Example of damped vibration — A tuning fork when stroked on a rubber pad, executes the damped vibrations in air.
(iii) The amplitude of vibrations decreases due to the frictional force.
The frictional force at any instant is proportional to the velocity of the body and it has the tendency to resist the motion.
As a result, the energy of the vibrating body continuously dissipates in doing work against the force of friction and so its amplitude gradually decreases.
(iv) After some time, when the body has lost all its energy, it stops vibrating.
Related Questions
Draw a sketch showing the displacement against time for a body executing the damped vibrations.
Explain why strings of different thickness are provided on stringed instrument.
[Hint — Natural frequency of vibration of a stretched string is inversely proportional to the radius (or thickness) of string so notes of different frequencies can be obtained by producing vibrations in the different strings]
What are the damped vibrations? How do they differ from free vibrations? Give one example of each.
What is meant by resonance? Describe a simple experiment to illustrate the phenomenon of resonance and explain it.