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Sound Waves & Beats

Last updated almost 6 years ago

5 questions

1

Question 1

1.

When guitar strings A and B are plucked at the same time, a beat frequency of 4 Hz is heard. If string A is tightened, the beat frequency decreases to 3 Hz.

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Question 2

2.

A person in the distance is hammering a nail into a board. You see the hammer strike the nail before you hear the sound. Explain.

Question 3

3.

1. The wavelength of sound coming from a loudspeaker is doubled.
a. Does the frequency of the sound waves increase, decrease, or stay the same? Explain.
b. Does the speed of the sound waves increase, decrease, or stay the same? Explain.

Question 4

4.

Dolphins of the open ocean are classified as Type II Odontocetes (toothed whales). These animals use ultrasonic “clicks” with a frequency of 55kHz to navigate and find prey.
a. Suppose a dolphin sends out a series of clicks that are reflected back from the bottom of the ocean 75m below. How much time elapses before the dolphin hears the echo’s of the clicks? (The seed of sound in seawater is 1530 m/x)
b. What is the wavelength of a 55kHz sound in the ocean?

Question 5

5.

To tune middle C on a piano, a tuner hits the key and at the same time sounds a 261-Hz tuning fork. If the tuner hears three beats per second, what are the possible frequencies of the piano key?