Sound Waves 222

The diagrams show the sound waves produced in one second from various tuning forks. Which sound wave has the lowest pitch?

A

Which best explains why sound travels fastest through a solid? Sound is a mechanical wave, so closer molecules in the medium cause energy to transfer faster. Sound is a mechanical wave, so if the volume of the medium is greater, more energy is transferred. Sound is an electromagnetic wave, so the medium does not affect the speed. Sound is an electromagnetic wave, so a greater amplitude results in a greater speed.

Sound is a mechanical wave, so closer molecules in the medium cause energy to transfer faster.

The figure shows a sound wave as a function of time when the source is stationary with respect to the observer. An Illustration of a transverse wave and four crests and four troughs are labeled 1 s total. Which shows the perceived sound wave heard by a stationary observer when the source moves toward the observer?

D

What is the name of the perceived change in a sound wave's frequency due to motion between the observer and the sound source? diffraction Doppler effect reflection resonance

Doppler effect

Juan is standing on the street. An ambulance moves toward him and then passes by. What best describes the pitch that Juan hears? The pitch remains constant as the ambulance moves toward and then away from Juan. The pitch increases and decreases in a repeated pattern as the ambulance passes Juan. The pitch drops to a lower pitch once the ambulance passes by Juan. The pitch increases to a higher pitch once the ambulance passes by Juan.

The pitch drops to a lower pitch once the ambulance passes by Juan.

A guitar string is plucked. What best describes the formation and transmission of the sound wave? The string vibrates the surrounding air, which produces a transverse wave. The string vibrates the surrounding air, which produces a longitudinal wave. The string produces a longitudinal wave that travels without a medium. The string produces a transverse wave that travels without a medium.

The string vibrates the surrounding air, which produces a longitudinal wave.

Which voice can produce a pitch that has a speed of 343 m/s and a wavelength of 0.68 m? Check all that apply. bass baritone tenor contralto soprano

contralto soprano

An illustration of a ringing bell and dots representing air molecules. The dots are close together, then far apart and close together again representing a longitudinal mechanical wave of sound going from the bell to an ear. How many wavelengths are seen in this image of a sound wave? three four six ten

four

A student hears a police siren. What would change the frequency that the student hears? Check all that apply. if the student walked toward the police car if the student walked away from the police car if the police car moved toward the student if the police car moved away from the student if the intensity of the siren increased if the intensity of the siren decreased

if the student walked toward the police car if the student walked away from the police car if the police car moved toward the student if the police car moved away from the student

What best describes a sound wave? transverse and electromagnetic longitudinal and mechanical longitudinal and electromagnetic transverse and mechanical

longitudinal and mechanical

An ambulance emits a frequency of 450 Hz from its siren. What frequency is heard by a man as the ambulance moves toward him? less than 450 Hz more than 450 Hz 450 Hz 0 Hz

more than 450 Hz

A source emits a sound and is represented by the red dot in this map. Four people are located around the source, and the circles represent the sound wave. An illustrations with circles spreading out from a point. On the left the spacing is very close together and on the right the spacing is farther apart. There is an A farthest left and a D farthest right. Just to the right of the dot is C and bove that B. As the source moves west, which person hears the highest pitch? person A person B person C person D

person A

is the perceived frequency of a sound wave.

pitch

A sound wave travels through air. In which regions are air molecules the least dense? compressions frequencies pitches rarefactions

rarefactions

What two factors affect the speed of a sound wave as it travels through a medium? the energy transferred by the wave and the density of the medium the type of medium and the energy transferred by the wave the type of medium and the temperature of the medium the temperature of the medium and the energy transferred by the wave

the type of medium and the temperature of the medium

Sound will travel slowest through which medium? water at 55°C water at 75°C ice at 0°C ice at -25°C

water at 55°C

Noah and Nina are 15 m apart in a closed room. Noah says the same sentence twice. The first time, Nina does not hear the sound, but she does hear the sentence the second time. What best describes the difference between the second sound wave and the first? The second sound wave reflects off the walls of the room, so Nina is able to hear the sound. The second sound wave travels faster to Nina, so less energy is dissipated through the air. The air molecules in the compressions of the second wave are more dense. The air molecules in the second wave are closer together on average, so they travel faster.

The air molecules in the compressions of the second wave are more dense.