Name: Date: Period: Physics: Study guide concepts for waves and sound Waves Sound What is a wave? Identify parts of a wave (amplitude, frequency, period, wavelength) Constructive and destructive interference Compare/contrast longitudinal and transverse waves Relate/solve for wave speed, velocity of wave, and frequency Relate/solve for tension in a string, wave speed, and linear density Explain how standing waves are formed Explain how sound travels and how speed is a function of temperatures Be able to draw and solve for fundamental frequencies and harmonics for strings and open or closed pipes Solve for speed of sound in dry air Find frequency of beats Explain Doppler effect Part I: Free Response 1. What characteristics of motion define SHM? 2. How do transverse and longitudinal waves differ? How do they compare? 3. You are at a street corner and hear an ambulance siren. Without looking (and other than how loud it is), how can you tell when the ambulance passes by? 4. As a result of a distant explosion, an observer first senses a ground tremor, and then hears the explosion. What accounts for this time lag? 5. Although soldiers are usually required to march together in step, they must break their march when crossing a bridge. Explain the possible danger of crossing a rickety bridge without taking this precaution. 6. A spring with a spring constant of 1.8 x 10 2 N/m is attached to a 1.5 kg mass and then set in motion. a. What is the period of the mass-spring system? b. What is the frequency of the vibration of the system?
c. If another spring is attached in parallel (side by side so both springs attach so it is a double spring system, what will be the new period? 7. A simple pendulum consists of a small ball suspended so that its center of mass is exactly 0.800 m below the point of suspension. a. Calculate the period and frequency at a point near the earth s surface. b. Calculate the acceleration due to gravity if the pendulum were placed on the planet Venus and its period measure to be 1.89 s. 8. Identify or calculate the following for the wave provided: a. Nodes b. Antinodes c. Calculate the wavelength d. What is the Amplitude? e. If the frequency is 15 Hz, what is its speed? 9. A rope is tied to an oscillating saw blade and produces standing waves. The length of the rope is 5.00 m. There are 7 antinodes produced. a. Sketch the wave b. How many nodes are there? c. What is the wavelength? 13. A pendulum bob is released from its position of maximum potential energy and moves in the negative direction. Draw and write the general equation for its motion. Draw the general shapes of the velocity and acceleration graphs for this motion.
14. The eardrum, which transmits vibrations to the sensory organs of your ear, lies at the end of the ear canal. The ear canal in an average adult is 2.5 cm long. What frequency standing waves can occur within the ear canal that is within the range of human hearing? The speed of sound in the warm air of the ear canal is 350 m/s. What are the next 2 harmonic frequencies? 15. Wind instruments have an adjustable joint to change the tube length (an open pipe). Players know that they may need to adjust this joint to stay in tune that is, to stay at the correct frequency. To see why, suppose a cold flute plays the note A at 440 Hz when the air temperature is 20 C. a. How long is the tube? At 20 C, the speed of sound in air is 343 m/s. b. As the player blows air through the flute, the air inside the instrument warms up. Once the air temperature inside the flute has risen to 32 C, increasing the speed of sound to 350 m/s, what is the frequency? c. At the higher temperature, how must the length of the tube be changed to bring the frequency back to 440 Hz? Part II: Multiple Choice 1. What mass should be attached to a vertical spring with a spring constant of 39.5 N/m so that the natural vibration frequency of the system will be 1.00 Hz? a. 1.00 kg b. 2.00 kg c. 6.29 kg d. 39.5 kg
2. A tube that is open at both ends supports standing wave at 300 Hz and 400 Hz, with no harmonics in between. What is the fundamental frequency of the tube? a. 50 Hz b. 100 Hz c. 150 Hz d. 200 Hz e. 300 Hz 3. Two pendulums, A and B, have the same length. Pendulum A has a period of T. The bob on pendulum A is twice as heavy as the bob on pendulum B. What is the period of pendulum B? a. 0.71 T b. T c. 1.4 T d. 2 T 4. What is the length of the shortest closed pipe that will have a fundamental frequency of 60 Hz on a day when the speed of sound is 340 m/s? a. 1.24 m b. 1.42 m c. 2.14 m d. 4.12 m 5. In a pipe closed at one end resonates when the pipe is 22 cm long and a 384 Hz tuning fork is struck above its open end. This tuning fork does not resonate for any smaller pipe. Which of the following lengths will also result in resonance? a. 11 cm b. 44 cm c. 66 cm d. 88 cm e. 384 cm 6. A string is firmly attached at both ends. When a frequency of 60 Hz is applied, the string vibrates in the standing wave patter shown above. 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? a. 30 Hz b. 40 Hz c. 80 Hz d. 100 Hz e. 180 Hz
7. As sound travels from steel to air, both its speed and its: a. wavelength increase b. wavelength decrease c. frequency increase d. frequency decrease e. frequency remains unchanged 8. Assume that waves are propagating in a uniform medium. If the frequency of the wave source doubles then a. The speed of the wave doubles b. The wavelength of the wave doubles c. The speed of the wave halves d. The wavelength of the wave halves 9. One stereo loudspeaker produces a sound with a wavelength of 0.68 m while the other speaker produces sound with a wavelength of 0.65 m. What would be the resulting beat frequency? Assume the speed of sound to be 343 m/s. a. 3 Hz b. 23 Hz c. 66.5 Hz d. 500 Hz e. 11333 Hz 10. A place of zero displacement on a standing wave is called a. An antinode b. A node c. The amplitude d. The wavenumber e. The harmonic 11. A small vibrating object S moves across the surface of a ripple tank producing the wave fronts shown to the right. The wave fronts move with speed v. The object is traveling in what direction and with what speed relative to the speed of the wave fronts produced? Direction Speed a. To the right Equal to v b. To the right Less than v c. To the right Greater than v d. To the left Less than v e. To the left Greater than v