Measuring the Wave Speed on a Wave Demonstrator - Answers

The following table includes data and calculated wave speeds for each of these standing wave movies. You can compare your calculated wave speeds with those values.

Wave Velocity Calculations for Waves on a Wave Demonstrator
ƒ (Hz) N λ(m) vcalc (m·s-1) vobs (m·s-1)
0.883 2 1.80 1.59 1.42
1.608 3 0.90 1.45 1.42
2.361 4 0.60 1.42 1.42
3.217 5 0.45 1.45 1.42
3.951 6 0.36 1.42 1.42
4.771 7 0.30 1.43 1.42
5.617 8 0.26 1.44 1.42
6.396 9 0.23 1.44 1.42
7.185 10 0.20 1.44 1.42
N = number of nodes.
D = 0.148 m = inside diameter of metal ring.
λ = 2L/(N - 1)
vcalc = ƒλ
L = 0.90 m = length of wave demonstrator. Δt = 1.27 s = the time for the wave pulse to travel from one end of the demonstrator to the other and back, a distance of 1.80 m, so vobs = 1.42 m/s

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