3.4

Question 1

Denser materials have an increased mass of particles that are closer
together, this allows sound waves to transmit more efficiently.
Denser medium ∝ faster sound

Answer 1

Density

Question 2

Medium with higher temperature has faster moving particles that facilitate the transmission of sound waves more efficiently.
Higher temperature ∝ faster sound
Speed of sound at 0°C at 1 atm is 331 m/s
The speed increases approximately 0.60 m/s for each centigrade increase in temperature.

v = 331 m⁄s + 0.6 m⁄s T°C

Answer 2

Temperature

Question 3

• the reflected sound.
• must travel a minimum distance of 34.3 m for it to be perceived clearly
  o the distance between the source and the reflecting surface should be half this
  distance.

Answer 3

Echo

Question 4

• happens when there is no recognizable time delay between the perception of the
  original and the reflected sound waves.
• occurs when the time interval between the original and reflected sound is 0.1 s

Answer 4

Reverberation

Question 5

The reflected sound waves are coherent; the
direction and intensities of both the reflected and
incident sound are maintained
Reflected sound waves are focused to a point.
More sound waves get reflected than absorbed
because these surfaces have high reflection
coefficient.

Answer 5

Smooth and Rigid Surfaces

Question 6

Due to the irregular shape, the sound waves are reflected in various
directions, diffusing it.
More sound waves get absorbed by soft, porous surfaces.

Answer 6

Rough and Soft Surfaces

Question 7

1. A horn on a boat sounds a warning, and the sound penetrates the water. How does the
   frequency of the sound in the air compare to its frequency in the water? How does the
   wavelength in the air compare to the wavelength in the water?
   a. The frequency in the air is smaller than the frequency in the water, and the
   wavelength in the air is greater than the wavelength in the water.
   b. The frequency in the air is greater than the frequency in the water, and the
   wavelength in the air is smaller than the wavelength in the water.
   c. The frequency in the air is the same as the frequency in the water, and the
   wavelength in the air is the same as the wavelength in the water.
   d. The frequency in the air is the same as the frequency in the water, and the
   wavelength in the air is smaller than the wavelength in the water.
   e. The frequency in the air is the same as the frequency in the water, and the
   wavelength in the air is greater than the wavelength in the water.

Answer 7

d. The frequency in the air is the same as the frequency in the water, and the
wavelength in the air is smaller than the wavelength in the water.

Question 8

2. An echo is sound that returns to you after being reflected from a distant surface (e.g., the
   side of a cliff). Assuming that the distances involved are the same, an echo under water
   and an echo in air return to you ______________.
   a. at different times, the echo under water returning more slowly
   b. at different times, the echo under water returning more quickly
   c. at the same time

Answer 8

b. at different times, the echo under water returning more quickly