The Ungerecht Family Tree

string, frequency, antinodes: Adjacent antinodes are separated by a distance of 20 cm and waves travel at a speed of 1200 cm/s along the string. What frequency is the string vibrating at?

Ends of a stretched string are called nodes, N. Point of highest vibrational amplitude is antinode, A. Number of N-1 = harmonic full sine wave (2N) = wavelength

wavelength = 40 cm

freq = v/wavelength, v = velocity of wave
1200/40 = 30

Doppler effect ⇒ F = Fo (v +/- vo) / (v +/- vs)

v = velocity (343 m/s for speed of sound)
vo = velocity of observer (negative if moving away from source)
vs = velocity of source (negative if approaching observer)