Ms Lim's Cheat Sheet : Sound

Question 1

What is the source of sound?

Answer 1

A vibrating source.

Question 2

What are compression and rarefactions?

Answer 2

Compression is the most compressed part of a wave where the surrounding air pressure is the highest. Whereas, rarefaction is the least compressed part of a wave where the surrounding air pressure is the lowest.

Question 3

What is one wavelength in Sound?

Answer 3

One wavelength is from the centre of compression to the centre of the next compression.

Question 4

How does sound travel?

Answer 4

The vibration of (object) causes the surrounding air particles to vibrate in parallel to the direction of the sound wave. This creates a series of compressions and rarefactions which carries energy to the other end in the form of longitudinal wave.

Question 5

Why does sound travel faster in solids than in air?

Answer 5

Solid particles are closely packed while air particles are very far apart. Therefore, sound can be transferred quickly from one end to the other end.

Question 6

How does frequency, wavelength, and speed change when sound enters from air into water?

Answer 6

• Frequency always remains the same because the source of the sound did not change.
• Speed of sound increases when in water.
• Hence, by v+fλ, wavelength also increases.

Question 7

Define echo.

Answer 7

Echo is where sound is able to reflect.

Question 8

Why does amplitude decrease when you compare the reflected pulse to the transmitted pulse?

Answer 8

Some energy is transferred away to the surrounding when the wave propagates.
Some energy is also absorbed by the object when a sound wave reflects off a surface.

Question 9

Compare Pitch and Loudness.

Answer 9

• The higher the frequency, the higher the pitch.
• The larger the amplitude, the louder the sound is.