Question

Q1: In your own words, describe what you believe to be the differences between a standing wave in a string and a sound wave. Q2: In your own words, describe what you believe to be the similarities between a standing wave in a string and a sound wave. Q3: If a sound wave travels down a tube with a closed end (like a bottle) what happens to the wave when it gets to the closed end? 04: Why do you think you can get a sound to come out of a pop bottle by blowing into it? sounds they make? Why? Q5: List some other objects that make a sound when blown into just the right way. Do they differ in the

Answer 1

The differences between standing waves on a string and standing sound waves in a pipe are the traveling sound waves are reflected at the two ends of the pipe. At the end of a pipe they are open to the air, the pressure at the end of the pipe cannot oscillate. Standing waves on a strings are analogous to the resonant oscillation of a mass and spring. sound waves are longitudinal waves and the particle motion associated with a standing sound wave in a pipe is directed along the length of the pipe , back and forth along the pipe axis or left and right horizontally .

Standing waves can be set up in a tube of air, such as that in an organ pipe, as the result of interference between longitudinal sound waves traveling in opposite directions. The phase relationship between the incident wave and the wave reflected from one end of the pipe depends on whether that end is open or closed. This relationship is analogous to the phase relationships between incident and reflected transverse waves at the end of a string when the end is either fixed or .free to move.

In terms of the motion of particles of a medium in which there are sound waves     (longitudinal), describe one similarity and two differences between a progressive sound wave and a stationary (standing) sound wave. Similarity between standing wave in a string and sound wave are air particles vibrate parallel to the direction of wave travel. For a progressive wave amplitude of particles are same, but for stationary waves amplitude of particles varies from zero at the nodes to maximum the antinodes. For progressive wave particles within a wavelength has a different phase angle, but for stationary wave particles are in phase with one another in the same segment, and in anti-phase with the particles in the adjacent segments.

In a pipe closed at one end, the closed end is a displacement node because the wall at this end does not allow longitudinal motion of the air molecules. As a result, at a closed end of a pipe, the reflected sound wave is 180° out of phase with the incident wave. Furthermore, because the pressure wave is 90° out of phase with the displacement wave, the closed end of an air column corresponds to a pressure antinode (that is, a point of maximum pressure variation).
The open end of an air column is approximately a displacement antinode and a pressure node. We can understand why no pressure variation occurs at an open end by noting that the end of the air column is open to the atmosphere; thus, the pressure at this end must remain constant at atmospheric pressure