William Moebs; Samuel J. Ling; Jeff Sanny

Additional Problems

A 0.80-m-long tube is opened at both ends. The air temperature is $26 ° C .$ The air in the tube is oscillated using a speaker attached to a signal generator. What are the wavelengths and frequencies of first two modes of sound waves that resonate in the tube?

130.

A tube filled with water has a valve at the bottom to allow the water to flow out of the tube. As the water is emptied from the tube, the length L of the air column changes. A 1024-Hz tuning fork is placed at the opening of the tube. Water is removed from the tube until the $n = 5$ mode of a sound wave resonates. What is the length of the air column if the temperature of the air in the room is $18 ° C?$

Picture shows a tuning fork placed above the opening of the tube filled with the water. Water is removed from the tube for the distance L.

131.

Consider the following figure. The length of the string between the string vibrator and the pulley is $L = 1.00 m .$ The linear density of the string is $μ = 0.006 kg/m .$ The string vibrator can oscillate at any frequency. The hanging mass is 2.00 kg. (a)What are the wavelength and frequency of $n = 6$ mode? (b) The string oscillates the air around the string. What is the wavelength of the sound if the speed of the sound is $v_{s} = 343.00 m/s$ ?

Picture shows a string vibrator connected to a frictionless pulley with a hanging mass of m. The distance of the string connecting the vibrator to the pulley is L.

132.

Early Doppler shift experiments were conducted using a band playing music on a train. A trumpet player on a moving railroad flatcar plays a 320-Hz note. The sound waves heard by a stationary observer on a train platform hears a frequency of 350 Hz. What is the flatcar’s speed in mph? The temperature of the air is $T_{C} = 22 ° C$ .

133.

Two cars move toward one another, both sounding their horns $(f_{s} = 800 Hz)$ . Car A is moving at 65 mph and Car B is at 75 mph. What is the beat frequency heard by each driver? The air temperature is $T_{C} = 22.00 ° C$ .

134.

Student A runs after Student B. Student A carries a tuning fork ringing at 1024 Hz, and student B carries a tuning fork ringing at 1000 Hz. Student A is running at a speed of $v_{A} = 5.00 m/s$ and Student B is running at $v_{B} = 6.00 m/s .$ What is the beat frequency heard by each student? The speed of sound is $v = 343.00 m/s .$

135.

Suppose that the sound level from a source is 75 dB and then drops to 52 dB, with a frequency of 600 Hz. Determine the (a) initial and (b) final sound intensities and the (c) initial and (d) final sound wave amplitudes. The air temperature is $T_{C} = 24.00 ° C$ and the air density is $ρ = 1.184 {kg/m}^{3} .$

136.

The Doppler shift for a Doppler radar is found by $f = f_{R} (\frac{1 + \frac{v}{c}}{1 - \frac{v}{c}})$ , where $f_{R}$ is the frequency of the radar, f is the frequency observed by the radar, c is the speed of light, and v is the speed of the target. What is the beat frequency observed at the radar, assuming the speed of the target is much slower than the speed of light?

137.

A stationary observer hears a frequency of 1000.00 Hz as a source approaches and a frequency of 850.00 Hz as a source departs. The source moves at a constant velocity of 75 mph. What is the temperature of the air?

138.

A flute plays a note with a frequency of 600 Hz. The flute can be modeled as a pipe open at both ends, where the flute player changes the length with his finger positions. What is the length of the tube if this is the fundamental frequency?