The sound wave travels in all directions. The skin of a drum is a thin sheet of plastic or animal skin stretched tightly across a frame. It vibrates when struck with drumsticks. The vibration shakes the air nearby and spreads out as sound waves. Let's take a look at an example. Imagine a church bell.
When a bell rings, it vibrates, which means the bell itself flexes inward and outward very rapidly. As the bell moves outward, it pushes against particles of air. Those air particles then push against other adjacent air particles, and so on. As the bell flexes inward, it pulls against the adjacent air particles, and they, in turn, pull against other air particles. This push and pull pattern is a sound wave. The vibrating bell is the original disturbance, and the air particles are the medium.
Sound isn't restricted to moving through the air. Press your ear against a solid surface like a table and close your eyes. Tell someone else to tap his or her finger on the other end of the table. All sounds begin with vibration. Can you hear the vibrations of your hands? Place all of the volunteers in a line, facing the class, with 3—4 feet of space separating them.
Ask the students to act out the following sequence of events: The first student rings the bell or other sound-making device. The second student air molecule begins to vibrate wiggle , moves toward the third student air molecule and touches them. The third student, feeling the touch of the second student, starts to vibrate and move towards the fourth student.
In the meantime, the second student returns to their original place. The vibration continues down the line until it reaches the last student, who bangs the drum eardrum when the last air molecule reaches them. Run through it a second time with more speed. Can sound exist in space outside of the space shuttle? Hint: No. Sound needs a medium e. This process continues in consecutive fashion, with each individual particle acting to displace the adjacent particle.
Subsequently the disturbance travels through the slinky. As the disturbance moves from coil to coil, the energy that was originally introduced into the first coil is transported along the medium from one location to another. A sound wave is similar in nature to a slinky wave for a variety of reasons. First, there is a medium that carries the disturbance from one location to another.
Typically, this medium is air, though it could be any material such as water or steel. The medium is simply a series of interconnected and interacting particles. Second, there is an original source of the wave, some vibrating object capable of disturbing the first particle of the medium. The disturbance could be created by the vibrating vocal cords of a person, the vibrating string and soundboard of a guitar or violin, the vibrating tines of a tuning fork, or the vibrating diaphragm of a radio speaker.
Third, the sound wave is transported from one location to another by means of particle-to-particle interaction. If the sound wave is moving through air, then as one air particle is displaced from its equilibrium position, it exerts a push or pull on its nearest neighbors, causing them to be displaced from their equilibrium position.
This particle interaction continues throughout the entire medium, with each particle interacting and causing a disturbance of its nearest neighbors.
Since a sound wave is a disturbance that is transported through a medium via the mechanism of particle-to-particle interaction, a sound wave is characterized as a mechanical wave. The creation and propagation of sound waves are often demonstrated in class through the use of a tuning fork.
A tuning fork is a metal object consisting of two tines capable of vibrating if struck by a rubber hammer or mallet. As the tines of the tuning forks vibrate back and forth, they begin to disturb surrounding air molecules.
0コメント