Glossary of Physics Terms and Concepts

• sound - consists of density waves, patterns of compressions, and rarefactions that travel outward from their source at the speed of sound (331 meters per second in air)
  
• tone - what is heard when fluctuations of sound are repetitive, with a pitch equal to the fluctuation's frequency
  
• pitch - the frequency of a sound
  
• frequency - the number of cycles completed by an oscillating system in a certain amount of time (SI unit is hertz)
  
• note - letters that are assigned at specific intervals at a standard pitch
  
• tension - outward forces on an object that tend to stretch it
  
• springlike force - a force that is proportional to displacement, consistent with Hooke's law
  
• modes - a basic pattern of distortion or oscillation
  
• harmonic oscillator - an oscillator in which the restoring force on an object is proportional to its displacement from a stable equilibrium. The period of a harmonic oscillator does not depend on the amplitude of its motion
  
• mechanical wave - a natural and often rhythmic motion of an extended object about its stable equilibrium shape or situation
  
• standing wave - a wave in which all the nodes and antinodes remain in place
  
• transverse wave - a wave in which the underlying oscillation is perpendicular to the wave itself
  
• higher-order vibrational modes - a vibrational mode that is more complicated that the fundamental mode and in which different parts of the extended system move in opposite directions
  
• harmonics - integer multiples of the fundamental frequency of oscillation for a system. The second harmonic is twice the frequency of the fundamental, and the third harmonic is three times the frequency of the fundamental. Harmonics can continue forever.
  
• timbre - the mixture of tones in an instrument's sound that are characteristic of that instrument
  
• superposition - the overlapping of two or more waves so that their amplitudes add together and they form a combined wave
  
• resonant energy transfer - the gradual transfer of energy to or from a natural resonance causes by small forces timed to coincide with a particular part of each oscillatory cycle
  
• sliding friction - the forces that resist relative motion as two touching surfaces slide across one another