A train whistle is heard at 270 Hz as the train approaches town. The train cuts its speed in half as it nears the station, and the sound of the whistle is then 260 Hz. Part A What is the speed of the train before slowing down? Express your answer to two significant figures and […]

## Problem 15.50

An echocardiogram uses 4.4 MHz ultrasound to measure blood flow in the aorta. The blood is moving away from the probe at 1.2 m/s . Part A What is the frequency shift of the reflected ultrasound? Use values given in the table if necessary. Enter a positive value if the received frequency is higher than […]

## Problem 15.43

A rock band playing an outdoor concert produces sound at 120 dB 5.0 m away from their single working loudspeaker. Part A What is the sound intensity level 35 m from the speaker? Express your answer using two significant figures.

## Problem 15.42

A concert loudspeaker suspended high off the ground emits 39 W of sound power. A small microphone with a 1.0 cm2 area is 56 m from the speaker. Part A What is the sound intensity at the position of the microphone? Express your answer to two significant figures and include the appropriate units. Part B […]

## Problem 15.33

A large solar panel on a spacecraft in Earth orbit produces 1.6 kW of power when the panel is turned toward the sun. Part A What power would the solar cell produce if the spacecraft were in orbit around Saturn, 9.5 times as far from the sun? Express your answer to two significant figures and […]

## Problem 15.30

At a rock concert, the sound intensity 1.0 m in front of the bank of loudspeakers is 0.10 W/m2. A fan is 30 m from the loudspeakers. Her eardrums have a diameter of 8.4 mm. Part A How much energy is transferred to each eardrum in 1.0 second? Express your answer using two significant figures. […]

## Problem 15.28

Part A An FM radio station broadcasts at a frequency of 101.3 MHz. What is the wavelength? Part B What is the frequency of a sound source that produces the same wavelength in 20∘ C air?

## Problem 15.22

People with very good pitch discrimination can very quickly determine what note they are listening to. The note on the musical scale called C6 (two octaves above middle C) has a frequency of 1050 Hz. Some trained musicians can identify this note after hearing only 12 cycles of the wave. Part A How much time […]

## Problem 15.20

A boat is traveling at 1.2 m/s in the same direction as an ocean wave of wavelength 30 m and speed 6.8 m/s. Part A If the boat is on the crest of a wave, how much time will elapse until the boat is next on a crest? Express your answer to two significant figures […]

## Problem 15.17

A traveling wave has displacement given by y(x,t)=(2.0cm)×cos(2πx−4πt), where x is measured in cm and t in s. Part A What is the speed of the wave? Express your answer to two significant figures and include the appropriate units. Part B Draw a snapshot graph of this wave at t = 0 s (solid line). […]