What should I know?

1. Objects or particles that are held in place by a set of forces can be made to oscillate around their rest position due to the action of those restoring forces.
2. Restoring forces are related directly to the displacement of the object or particle.
3. Objects or particles can be displaced from their rest positions by doing work on them, which gives them potential energy. This energy is converted into kinetic energy by the restoring forces.
4. Objects or particles that are displaced from their rest positions will continue to move past their rest positions due to their inertia and the fact that the net force acting on the object or particle decreases to zero at the rest position.
5. Objects that show a repetitive vibration around a central point due to restoring forces that are proportional to the displacements of the objects are in simple harmonic oscillation or simple harmonic motion.
6. The period of oscillation (time of one full oscillation) is inversely related to the frequency of its oscillation.
7. If work is done on particles in a matrix, the energy added to the particles is transmitted to the neighboring particles through the restoring forces; this transmission of energy takes the form of a wave.
8. Waves come in two main types, based on a comparison of the directions of the vibration and the wave's propagation: in longitudinal waves, particles oscillate parallel to the direction of the wave's propagation; in transverse waves, the particles oscillate perpendicular to the wave's propagation.
9. Waves transmit energy through a medium, not matter.
10. Waves move at a speed that is dictated by the nature of the medium. No other wave property can affect the wave's speed.
11. Wave speed and frequency are related but often confused for each other.
12. A phenomenon is a wave if it exhibits the four wave behaviors:
    • reflection - a bouncing off a rigid boundary,
    • refraction - a bending as it moves from one type of medium to another,
    • diffraction - a bending around barriers, and
    • interference - interaction between two or more waves, which affects the total amplitude of particles in the medium at that point.
13. For a source moving through a medium, producing waves as it goes, the speed of the waves produced is not affected but the frequency of those wave changes based on the direction of motion of the source. This phenomenon is known as the Doppler effect.
14. For a source moving at a speed that is the same or greater than the waves it produces, the waves produced constructively interfere, creating a shock wave.
15. Sound is a type of longitudinal wave, which may be transmitted through many types of media, but is most commonly described as transmitted through air.
16. Waves in a closed tube or on a string with fixed ends can produce standing waves if oscillated at certain frequencies. Those frequencies are determined by the length of the tube or the string and the speed at which the waves propagate. Standing waves are also called harmonics due to the fact that they are closely associated with the notes produced by musical instruments.
17. Humans experience sound wave properties in different ways: the amplitude is related to the loudness of the sound experienced and the frequency of the sound wave is interpreted as the sound's pitch.
18. The range of hearing of a healthy young human is 20 to 20,000 Hz.
19. The range of loudness that can be experienced safely by a human is 0 to 120 decibels; above this range, permanent hearing loss will occur.
20. The musical nature of certain sounds results from the patterns produced; the human brain can decipher these patterns and appreciate their beauty.
21. Musical instruments produce the musical notes that they produce due to the length of their open- or closed-end tubes or strings.