People often think thatĬhanging the amplitude will change the speed of a All of these changes to the medium would affect the speed of sound. Or the density of the air, or you can swap out the airĮntirely for another material, like water or helium or a metal. The temperature of the air or the humidity of the air So, to change the speed of sound in air, you can change things like The properties of the medium that the sound wave is traveling in. So, how can we change the speed of sound? Well, the only way toĬhange the speed of sound is to change the medium or You can do to the speaker that would increase the speed of sound. If you increase the frequency, the wavelength will decreaseīy that same factor, and the speed of the sound The speed of the sound wave, but that's not what happens. When looking at this equation, you might think that if you adjust the setting on your speakerĪnd increase the frequency you'd also be increasing This formula is accurateįor all kinds of waves, not just sound waves, because a wave has to move one To be one over the period, we can rewrite this formula as speed equals wavelength times frequency. Since the wave is traveling forwards one wavelength per period, or since the frequency is defined To be the distance per time, the speed of a sound wave has to be the wavelength of the wave divided by the period of the wave. To be back where it started after one period. This is because the wave has to overlap with its initial shape after one period, because the molecule has Shape has moved forward one complete wavelength. It takes one period for this molecule to move back and forth The velocity of a sound wave, let's look closely at So, the speed of a sound wave can be found by finding the speed of the peaks or the speed of the valleys or the speed of any single Of the air displacement versus position of the air, we can see that as the wave travels the shape of this wave On the surface of water are examples of transverse waves. When the wave velocity points perpendicular to the We call sound a longitudinal wave because the wave is traveling parallel to the line traced out by the Moving with the speed, but by the speed of sound, we mean the speed of the disturbance as it moves through the air molecules. Note that the speed of sound does not mean the speed of the air moleculesĪs they move back and forth. The speed of the waveĬan again be determined by the speed of the compressed regions as they travel through the medium. We can also watch the speed of sound of a repeating simple harmonic wave. In non-humid air at 20 degrees Celsius, the speed of sound is about 343 meters per second Of this compressed region as it travels through the medium. We can find the speed of sound by looking at the speed The wave travels all the way to your ears, for you to enjoy.Make one short burst, we'll create a pulse wave. This is simply moving back and forth, like a heavy metal guitar string! The string oscillates back and forth at its resonant frequency, and pushes against molecules of air, which causes the air to push against other air molecules, creating a sound wave since the air is less dense. Resonance is when an object oscillates at a specific frequency that causes it to increase in amplitude. We hear the sounds emitted from solid objects because of resonance. So most sound waves in solids are just pressure waves. The waves are normally just pressure forces, like pushing an object, your hand pushes some molecules, which push other molecules, which push other molecules. Pressure waves are part of the same spectrum as sound waves, but are caused by faster waves. Because of this, the waves in a solid travel very very fast, and usually are too fast to be audible, and are considered to be more of pressure waves. This causes the molecules to be really close as solids are very dense, like the mosh pits of the most br00tal bands in existence. In solids, the molecules are composed in a lattice with a lot of strong intermolecular bonds. If the mosh pit were to spread out, the velocities of the waves would decrease, and the pit would be less intense, like a gas instead of a liquid. When the moshers push against each other, the velocities of the waves of them pushing each other get faster, because they are closer together. In a heavy metal gig, there are a lot of people (we're going to think of them as particles) closely compacted exerting repulsive forces on each other. In liquids, the speed of sound is faster because the molecules are more closely compacted, so the wave can propagate faster. This causes the velocity of the sound wave to normally be small, audible to our ears. Gases are less dense than liquids or solids, so when sound moves through them, the gas molecules bump into each other less frequently because they are more spread out. Sound waves are longitudinal waves, they propagate though space from particles colliding with each other.
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