Exam 20: Traveling Waves

A sound source emits 20.0 W of acoustical power spread equally in all directions. The threshold of hearing is 1.0 × 10^-12 W/m². What is the sound intensity level 30.0 m from the source?

Calculate the light intensity 1.51 m from a light bulb that emits 100 W of visible light, assuming that the light radiates uniformly in all directions.

A plane flies toward a stationary siren at 1/4 the speed of sound. Then the plane stands still on the ground and the siren is driven toward it at 1/4 the speed of sound. In both cases, a person sitting in the plane will hear the same frequency of sound from the siren.

A boy on a bicycle approaches a brick wall as he sounds his horn at a frequency 400.00 Hz. The sound he hears reflected back from the wall is at a frequency 408.00 Hz. At what is the speed is the boy riding his bicycle toward the wall? Assume the speed of sound in air is 340 m/s.

The intensity of sunlight falling on the earth is about 1.4 kW/m² (before any gets absorbed by our atmosphere). At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 10⁸ km and the earth's radius = 6.4 × 10³ km.)

A carousel that is 5.00 m in radius has a pair of 600-Hz sirens mounted on posts at opposite ends of a diameter. The carousel rotates with an angular velocity of 0.800 rad/s. A stationary listener is located at a distance from the carousel. The speed of sound is 350 m/s. The longest wavelength reaching the listener from the sirens is closest to

A transverse wave is traveling on a string stretched along the horizontal x-axis. The equation for the vertical displacement y of the string is given by y = 0.0020 cos[π(15x - 52t)], where all quantities are in SI units. The maximum speed of a particle of the string is closest to

The figure shows the displacement y of a wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the frequency of the wave.

The density of aluminum is 2700 kg/m³. If transverse waves propagate at 34 ,s in a 4.6-mm diameter aluminum wire, what is the tension on the wire?

For the wave shown in the figure, the frequency is

Ocean tides are waves that have a period of 12 hours, an amplitude (in some places) of 1.50 m, and a speed of 750 km/hr. What is the distance between adjacent crests of these waves?

If the intensity level at distance d of one trombone is 70 dB, what is the intensity level of 76 identical trombones, all at distance d?

At a distance of 2.00 m from a point source of sound, the intensity level is 80.0 dB. What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10^-12 W/m².

For the wave shown in the figure, the wavelength is

The vertical displacement y(x,t) of a string stretched along the horizontal x-axis is given by y(x,t) = (6.00 mm) cos[(3.25 m^-1)x - (7.22 rad/s)t]. (a) What is the minimum time for each complete cycle of the wave? (b) What is the distance between adjacent crests of the wave? (c) How fast does this wave travel?

A factory siren indicating the end of a shift has a frequency of 90.0 Hz. The speed of sound is 343 m/s. (a) What frequency is perceived by the occupant of a car traveling towards the factory at 25.0 m/s? (b) What frequency is perceived by the occupant of a car traveling away from the factory at 30.0 m/s?

In the figure, which of the curves best represents the variation of wave speed as a function of tension for transverse waves on a stretched string?

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the wavelength of the wave.

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. How fast is the wave traveling?

A transverse wave traveling along a string transports energy at a rate r. If we want to double this rate, we could