Standing Waves
If the speed of sound in air is 340 m/s, the length of the organ pipe, open at both ends, that can resonate at the fundamental frequency of 136 Hz, would be:
1.25m
As sound travels from steel into air, what happens to it's velocity and frequency?
Velocity decreases, frequency is unchanged.
A block attached to an ideal spring undergoes simple harmonic motion about its equilibrium position with amplitude A. What fraction of the total energy is in the form of kinetic energy when the block is at position x = A ?
0
What happens when the frequency of the external force matches the natural frequency of the system?
resonance
According to the principle of superposition, what happens when two wave pulses with amplitudes of +3 cm and -1 cm meet at the same point?
They create a pulse with an amplitude of +2 cm.
For a standing wave mode on a string fixed at both ends, adjacent antinodes are separated by a distance of 20cm. Waves travel on this string at a speed of 1200 cm/s. At what frequency is the string vibrated to produce this standing wave?
30 Hz
When a train is at rest, both a passenger on the train and a ticket seller at the station agree that the trains whistle produces sound at a frequency of 120 Hz. When the train is moving away from the station at 15 m/s, the passenger hears a frequency of ___ Hz and the ticket seller hears a frequency of ____ Hz.
120Hz, 115Hz
A block with a mass of 10 kg connected to a spring oscillates back and forth with an amplitude of 2 m. What is the approximate period of the block if it has a speed of 4 m/s when it passes through its equilibrium point?
3.14s
How much energy must the shock absorbers of a 1200-kg car dissipate in order to damp a bounce that initially has a velocity of 0.800 m/s at the equilibrium position? Assume the car returns to its original vertical position.
384 J
What is the phase difference between two waves that results in "fully destructive" interference?
Pi
A resonance occurs with a tuning fork and an air column of size 39 cm. The next highest resonance occurs with an air column of 65 cm. What is the frequency of the tuning fork? Assume that the speed of sound is 343 m/s.
659.6 Hz
Given that the sound intensity level of a particular wave is 82 dB, what will be the sound intensity for that wave?
πΌ =1.6 Γ10β6 W/m2
A pendulum with a period of 2.00000 s in one location (π=9.80β’m/s2) is moved to a new location where the period is now 1.99796 s. What is the acceleration due to gravity at its new location?
9.82002m/s2
The amplitude of a lightly damped oscillator decreases by 3.0% during each cycle. What percentage of the mechanical energy of the oscillator is lost in each cycle?
5.91%
A guitar string is vibrating at 440Hz. A second string is plucked, and you hear a "wah-wah-wah" pulsing sound at a rate of 5Hz. You tighten the second string slightly, and the beat frequency increases to 8Hz. What was the original frequency of the second string?
445Hz
A tube of length L1 is open at both ends. A second tube of length L2 is closed at one end and open at the other end. This second tube resonates at the same fundamental frequency as the first tube. What is the value of L2?
Β½ L1
Suppose you are driving at a speed of 20.0 m/s and you hear the sound of a bell at a frequency of 400.0 Hz. What is the actual frequency of the bell if the speed of sound is 335 m/s?
425 Hz or 377 Hz
Suppose a diving board with no one on it bounces up and down in a SHM with a frequency of 4.00 Hz. The board has an effective mass of 10.0 kg. What is the frequency of the SHM of a 75.0-kg diver on the board?
1.37Hz
In a series LCR circuit at resonance, if you double the resistance, what happens to the resonant frequency?
Stays the same
Two speakers are separated by 3.0m and oscillate in phase at a frequency of 680Hz You stand directly in front of one speaker at a distance of 4.0m. Assume the speed of sound is 340m/s/ Do you hear a loud sound (constructive) or a quiet sound (destructive)?
constructive interference
A standing wave pattern is created on a guitar string as a person tunes the guitar by changing the tension in the string. Which of the following properties of the waves on the string will change as a result of adjusting only the tension in the string?
Speed and frequency
Two cars move toward one another, both sounding their horns (ππ =800Hz). 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 ππΆ=22.00Β°C.
ππ΄,beat=161.18Hz
ππ΅,beat=158.89Hz
A suspension bridge oscillates with an effective force constant of 1.00Γ108N/m. How much energy is needed to make it oscillate with an amplitude of 0.100 m?
500 kJ
As the damping constant is gradually increased in an underdamped system, what happens to the period of the oscillations? At what specific point does the period technically become "infinite"?
At the point of critical damping
Two identical speakers are emitting the same frequency. You are standing at a point where you hear total silence. One speaker is moved 0.2m closer to you, and suddenly you hear the maximum possible volume. What is the frequency of the sound? (Assume speed of sound is 340m/s).
850Hz