Waves

When the speed of an object exceeds the speed of sound, it is said to be traveling at supersonic speed.

• The speed of sound in air at standard temperature and pressure is approximately 343 meters per second (about 767 miles per hour).
• Any object moving faster than this speed is considered supersonic.
• When an object travels at supersonic speed, it can create shock waves in the air, which can result in a loud "sonic boom" when they reach an observer.

• The quality depends primarily on the waveform of the sound.
• The waveform of the sound emitted by a tuning fork is a simple sine curve.
• But most bodies vibrate in a very complex manner.
• Besides the fundamental frequency f, they consist of additional frequencies of 2f, 3f, 4f, etc.
• These additional tones are called overtones or harmonics.

Therefore, the strength of a wave is directly proportional to the square of its amplitude.

The frequency of the sound wave determines its pitch.

• Frequency refers to the number of vibrations or cycles of the sound wave that occur per second, measured in Hertz (Hz).
  
• High frequency sound waves correspond to high-pitched sounds (like a whistle or a flute).
  
• Low frequency sound waves correspond to low-pitched sounds (like a bass drum or a tuba). 
• While other factors like amplitude (loudness) and timbre (tone color) affect the overall perception of sound, it is primarily the frequency that our ears and brain interpret as the pitch of a sound.

The number of oscillations per second is called frequency.

The unit of frequency is Hertz (Hz), where 1 Hz is equal to one oscillation per second.

• It can be defined as the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings.

Therefore option (a) is correct.

The movement of an object going back and forth is called oscillation or vibration.

• These terms are often used interchangeably to describe a repetitive motion around a central equilibrium position.

It is usually denoted by the symbol T and its SI unit is second (s).

When the bob is displaced from its equilibrium position and released, it swings back and forth under the influence of gravity. This motion is called oscillation.