MYP Physics Sound Waves Notes

Sound Waves Transfer Energy Without Transferring Matter

1. Sound is produced when an object vibrates, disturbing the particles around it.
2. These vibrations cause nearby particles to vibrate, which then pass the disturbance to neighbouring particles.
3. Sound is classified as a mechanical wave, meaning it requires particles to transfer energy.
4. Sound cannot travel through a vacuum because there are no particles available to vibrate and pass on the energy.
5. This explains why sound cannot be heard in outer space.

Sound Is A Longitudinal Compression Wave

1. Sound in air is a longitudinal wave.
2. That means the particles of the medium vibrate parallel to the direction the wave travels.
3. The sound wave moves through the medium, but the particles do not move along with the wave.
4. Particles simply oscillate around their fixed positions.
5. Energy is transferred as vibrations pass from particle to particle.

Compression and Rarefaction

1. Compressions are regions where particles are close together.
2. These regions have higher pressure and higher density.
3. Rarefactions are regions where particles are farther apart.
4. These regions have lower pressure and lower density.
5. As the wave travels, compressions and rarefactions move through the medium.
6. The spacing between compressions represents the wavelength of the sound wave.

Media Through Which Sound Can Travel

1. Sound can travel through solids, liquids, and gases.
2. It cannot travel through a vacuum, for example, the space.
3. The speed of sound varies depending on the medium.
4. In general:
   1. Sound travels slowest in gases
   2. Faster in liquids