Question

Explain why, if we strike a table lightly, we hear a soft sound but if we hit the table hard, a loud sound is heard.
A. When a table is striked lightly, vibrations are produced with less amplitude
B. When the table is striked hard, the amplitude is high
C. Both
D. none

Answer 1

Hint: Study the concept of vibration. Learn how sound is produced from vibration of objects and on what properties the sound will depend on. Learn about the frequency and amplitude of vibration and the types of vibration depending on their frequency range.

Complete step by step solution:
Vibration can be defined as a phenomenon where an object oscillates about an equilibrium position. The vibration can be a regular vibration such as the motion of a pendulum or it can be an irregular one.
Sound wave are formed when a vibrating object make its surrounding medium vibrate
Amplitude of a vibration can be given as the maximum distance the object covers in either side of the equilibrium position.
Frequency of a vibration is given by the number of vibrations occurring per second. It can be explained as a vibrating object is in to and fro motion. A complete vibration occurs when an object moves from one extreme position to the other and again moves back to the first extreme position. The number of complete cycles that occurs in a second is called frequency of the vibration. Unit of frequency is Hz(hertz). One hertz is equal to one complete cycle per second.
Amplitude is measured in the units of distance. The more the amplitude of the vibration, the louder the sound will generate.
When we strike the table lightly, we have a smooth vibration with small amplitude and hence we get a soft sound.
When we strike the table hard, the vibration produced will have more amplitude and hence we hear a loud sound.
So, both option (A) and (B) are correct.
The correct option is (C).

Note: Vibration of frequency above 20,000 Hz is called ultrasound. Vibration of frequency below 20 Hz is called infrasound. We cannot hear ultrasound also. Human ears are capable of hearing frequencies between 20 Hz and 20,000 Hz. This frequency range is called audible range.