Day 1
Simple Harmonic Motion –back and forth repeating motion.
Properties of waves and SHM
Frequency () - # of oscillations that are completed each second.
#cycles (oscillations)
time (seconds)
UNIT: s-1 or Hertz(Hz)
Period (T) – the time for one oscillation to occur.
=1/T or T=1/
Tspring= 2m/k or Tpendulum=2l/g
Amplitude – magnitude of maximum displacement of the wave. Tells you how much energy there is.
Wavelength – distance between two successive points on a wave or one oscillation. ()
Day 2
Wave types
Transverse – particles vibrate perpendicular to direction of energy transfer
Longitudinal (compressional) – particles vibrate parallel to the direction of energy transfer.
***Waves only transmit energy. They do not transfer matter!!!***
Wave Interference
Principle of Superposition – 2 waves cross over one another and the result is a wave that is
different from either original wave.
Constructive interference – waves ‘add’ together to produce a larger wave.
Destructive interference – waves ‘add’ together to produce a smaller wave.
When two waves overlap in a specific way they create:
Standing Wave – a resultant wave pattern that does not appear to move along the string.
- two waves with the same frequency, wavelength, and amplitude that are traveling
through a medium
- Parts of a standing wave:
o Node – point on a standing wave with no energy. zero displacement.
o Antinode – point on a standing wave with max energy. max displacement.
o speed of a wave v=
Strings
Pitch – ‘highness’ or ‘lowness’ of a sound. corresponds to a sounds frequency
Factors that affect pitch – 1) the tension in the string
2) the length of the string
3) the mass of the string
These factors determine the speed a wave moves along a string.
v = (TL/M)
Frequencies on a string –
Fundamental Frequency – lowest possible frequency of a standing wave (n=1). AKA First Harmonic.
When drawing frequencies on a string you must always have a node at both ends.
Harmonics – multiples of the fundamental frequency. n is the harmonic number.
fn=nV
2L
First harmonic n=1 fn=1v
2L
Overtones – harmonics heard on top of the fundamental frequency. This gives
instruments their sound quality or ‘timbre’