Chapter 26, Problem 36A

If the handle of a tuning fork is held solidly against a table, the sound becomes louder. Why? How will this affect the length of the time the fork keeps vibrating? Explain, using the law of energy conservation.

To determine

To check why the sound becomes louder and how the length of time of vibration of fork gets affected when the handle of a tuning fork is held solidly against a table.

Answer to Problem 36A

When the handle of a tuning fork is held solidly against a table then due to large amplitude of vibrations, the sound becomes louder and the length of time of vibration of fork decreases.

Explanation of Solution

Introduction: It involves the concept of energy transfer in vibrations of the tuning fork.

kinetic energy of the tuning fork contains both amplitudes as well as frequency dependence. Loudness is related to the square of the amplitude of the sound wave as well as its frequency. When the tuning fork is held solidly against a table then more energy is required for the tuning fork to vibrate. This increase in energy will result in the sound become louder.

As we know from above of this question that more energy is required when a tuning fork is held solidly. This will result in larger amplitude vibrations of the tuning fork which makes the air molecules near it vibrating with larger amplitude. While setting air molecules in vibrations energy is transferred from tuning fork to air molecules resulting in lower energy of the tuning fork and thus the length of the time of vibration decreases.

Conclusion: When a tuning fork is held solidly against a table then an increase in energy of the tuning fork will make the sound louder and it length of time of vibration decreases.