Physics - Sound: Vibrations, volume, and pitch

Grade 4Cambridge (IGCSE)

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Sound is created by vibrations. A vibration is a rapid back-and-forth movement. When an object vibrates, it causes the particles in the surrounding medium to vibrate as well.

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dB

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Hz

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A high-pitched sound is produced by a high frequency of vibrations (e.g., a thin, short string), while a low-pitched sound is produced by a low frequency of vibrations (e.g., a thick, long string).

📐Formulae

f = \frac{\text{Number of Vibrations}}{\text{Time (s)}}

\text{Speed (v)} = \frac{\text{Distance (d)}}{\text{Time (t)}}

\text{Frequency (Hz)} \propto \frac{1}{\text{Length (L)}}

💡Examples

Problem 1:

120

Solution:

f = \frac{120}{2} = 60\text{ Hz}

Explanation:

Frequency is the number of vibrations per second. Dividing the total vibrations by the total time gives the frequency.

Problem 2:

256\text{ Hz}

Solution:

Fork B

Explanation:

512\text{ Hz} > 256\text{ Hz}

Problem 3:

680\text{ meters}

Solution:

v = \frac{680\text{ m}}{2\text{ s}} = 340\text{ m/s}

Explanation:

v = \frac{d}{t}