Sound and Wave Test

The diagram shows two points, A and B, on a wave train. How many wavelengths separate point A and point B?

• 0.5

• 0.75

• 1.0

• 1.5

• 3.0

A wave travels with a speed of v on a string of length L and mass M. The string is stretched to a tension force T. If the linear density is quadrupled, what is the new speed of the wave?

• 2v

• v/(square root of 2)

• v/2

• v*(square root of 2)

The diagrams provided represent five different standing sound waves set up inside of a set of organ pipes 1 m long. The C pipes are open/closed and the O pipes are open/open. Which of the following statements correctly relates the frequencies of the organ pipes shown?

• Cy is twice the frequency of Cx

• Oy is twice the frequency of Ox

• Cz is five time the frequency of Cx

• Ox is twice the frequency of Cx

An elastic string 10 meters long is fixed to two walls. The string vibrates as shown in the diagram with a frequency of 16 Hz. What is the speed of waves on this string?

• 4 m/s

• 8 m/s

• 40 m/s

• 80 m/s

• 160 m/s

A police car travels down the highway with its siren making a continuous sound of 1500 Hz. A motorcyclist is on the same highway. The motorcyclist and police car have the velocities shown in the diagrams below. In which case will the motorcyclist hear the highest frequency from the police car’s siren?

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Two wave pulses X and Y travel toward each other on the same string, as shown. Which of the following waveforms could appear on the string at any time after the instant shown? Select two answers.

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A small spherical device acts as a point source of sound waves. At a distance d from the surface of the device the intensity of the waves is measured as, I₀. At which distance would the intensity be measured as I₀/16?

• d/8

• d/4

• 4d

• 8d

A wave with a wavelength of 50 cm is traveling on a string. The graph below shows the position as a function of time for a point on the string. If the frequency of the wave is cut to half what is the average speed of the point?

• 3.6 m/s

• 0.8 m/s

• 1.1 m/s

• 2.2 m/s

A stationary source emits sound waves of frequency f and wavelength λ that travel through the air with speed v. If the frequency of the source is changed to 2f, what will be the wavelength and speed of the new wave?

• λ and 2v

• λ and 1⁄2v

• 2λ and v

• 1⁄2λ and v

A string is firmly attached at both ends. When a frequency of 60 Hz is applied, the string vibrates in the standing wave pattern shown. Assume the tension in the string and its mass per unit length do not change. Which of the following frequencies could NOT also produce a standing wave pattern in the string?

• 30 Hz

• 40 Hz

• 80 Hz

• 180 Hz