2. A string with a length of 0.9m that is fixed at both ends

a) What is the longest possible wavelength for the travelling waves that can

interfere to form a standing wave on this string? (First harmonic)

b) If waves travel at a speed of 120m/s on this string, what is the frequency

associated with the longest wave (first harmonic) ?

a.) 1.8 metre

b.) 66.67 Hz

Explanation: Given that the

Length L = 0.9m

Wavelength (λ) = 2L/n

Where n = number of harmonic

If n = 1, then

Wavelength (λ) = 2L = 2 * 0.9 = 1.8 m

b.)

If waves travel at a speed of 120m/s on this string, what is the frequency

associated with the longest wave (first harmonic) ?

Given that V = 120 m/s

V = Fλ

But λ = 2L, therefore,

F = V/2L

F = 120/1.8

F = 66.67 Hz