Question

A string is 2.4 m long, and the speed of sound along this string is 450 m/s. Calculate the frequency of the wave that would produce a first harmonic. Assume the string has nodes at both ends.

What I've Tried
Ln=2.4m
v= 450 m/s
f=?
n=2

Ln=(4-1)/4 * Wavelength
Wavelength = 2.4m/0.75m
=3.2m

Wavelength=v/f
f=v/wavelength
f=450 m/s / 3.2m
=140 hz.

The answer is 94 hz

Answer 1

well, if nodes at both ends then the wave is twice as long as the string, 4.8 meters (draw it with half a wave on the string and bulge in the middle)

how long does it take for 4/8 meters?
T = 4.8/450
so
f = 450/4.8 = 93.75 Hz which is 94 indeed