Question

The speed of sound in dry air at 20 °C is 343.5 m s-1, and the frequency of the sound from the note C# above middle C on the piano is 277.2 s-1(according to the American standard pitch scale). Calculate the wavelength of the sound and the time it will take to travel 49.2 m across a concert hall. Wavelength = (answer) m

Answer 1

Answer:

1.23917 m

0.14323 s

Explanation:

v = Speed of sound in dry air at 20 °C = 343.5 m/s

f = Frequency of note C# = 277.2 /s = 277.2 Hz

λ = Wavelength

$v=f\lambda\\\Rightarrow \lambda=\frac{v}{f}\\\Rightarrow \lambda=\frac{343.5}{277.2}\\\Rightarrow \lambda=1.23917\ m$

Wavelength = 1.23917 m

Distance the wave needs to travel is 49.2 m

Time = Distance / Speed

$\text{Time}=\frac{49.2}{343.5}=0.14323\ s$

Time taken for the sound to travel across the concert hall is 0.14323 s