Exam 17: Waves II

A source emits sound with a frequency of 1000 Hz. It and an observer are moving toward each other, each with a speed of 100 m/s. If the speed of sound is 340 m/s, the observer hears sound with a frequency of:

Two identical tuning forks vibrate at 256 Hz. One of them is then loaded with a drop of wax, after which 6 beats per second are heard. The period of the loaded tuning fork is:

If the speed of sound is 340 m/s, the shortest closed pipe which resonates at 218 Hz is:

A stretched wire of length 1.0 m is clamped at both ends. It is plucked at its center as shown. The three longest wavelengths in the wire are (in meters):

A stationary source generates 5.0 Hz water waves whose speed is 2.0 m/s. A boat is approaching the source at 10 m/s. The frequency of these waves, as observed by a person in the boat, is:

An organ pipe with both ends open is 0.85 m long. Assuming that the speed of sound is 340 m/s, the frequency of the third harmonic of this pipe is:

A 200-cm open organ with one end open pipe is in resonance with a sound wave of wavelength 270 cm. The pipe is operating in its:

A stationary source S generates circular outgoing waves on a lake. The wave speed is 5.0 m/s and the crest-to-crest distance is 2.0 m. A person in a motor boat heads directly toward S at 3.0 m/s. To this person, the frequency of these waves is:

Two small identical speakers are connected (in phase) to the same source. The speakers are 3 m apart and at ear level. An observer stands at X, 4 m in front of one speaker as shown. If the amplitudes are not changed, the sound he hears will be least intense if the wavelength is:

The largest number of beats per second will be heard from which pair of tuning forks?

The rise in pitch of an approaching siren is an apparent increase in its:

The sound intensity 5.0 m from point source is 0.50 W/m². The power output of the source is:

Two identical strings, A and B, have nearly the same tension. When they both vibrate in their fundamental resonant modes, there is a beat of 3 Hz. When string B is tightened slightly, to increase the tension, the beat frequency becomes 6 Hz. This means:

A stationary source emits a sound wave of frequency f. If it were possible for a man to travel toward the source at the speed of sound, he would observe the emitted sound to have a frequency of:

The standard reference sound level is about:

The Doppler shift formula for the frequency detected is where f ' is the frequency emitted, v is the speed of sound, v_D is the speed of the detector, and v_s is the speed of the source. Suppose the source is traveling at 5 m/s away from the detector, the detector is traveling at 7 m/s toward the source, and there is a 3 m/s wind blowing from the source toward the detector. The values that should be substituted into the Doppler shift equation are:

The lowest tone produced by a certain organ comes from a 3.0-m pipe with both ends open. If the speed of sound is 340 m/s, the frequency of this tone is approximately:

The speed of a sound wave is determined by:

A tuning fork produces sound waves of wavelength $\lambda$ in air. This sound is used to cause resonance in an air column, closed at one end and open at the other. The length of this column CANNOT be:

Consider two imaginary spherical surfaces of different radius, both centered on a point sound source emitting spherical waves. The power transmitted across the larger sphere is ________ the power transmitted across the smaller and the intensity at a point on the larger sphere is ________ the intensity at a point on the smaller.