Question

The frequency of the first harmonic produced in air column enclosed in a closed pipe is 300 Hz. If its length is 40 cm, then what is the velocity of the sound in air?

• A. 320 m s^-1
• B. 340 m s^-1
• C. 400 m s^-1
• D. 480 m s^-1

Answer 1

The correct option is D

480 m s^-1

Correct option is D: $480m{s}^{-1}$

Step 1: Given:

Frequency $\left(f\right)=300Hz$

Length of string $\left(l\right)=40cm=0.4m$

Find: Velocity of the sound in air $\left(v\right)=?$

Step 2: finding velocity:

The frequency of the first harmonic produced in air column enclosed in a closed pipe can be found as,

$$\begin{gathered} \left(f\right)=\frac{v}{4l} \\ v=f\times 4l \\ v=300hz\times 4\times 0.4m \\ v=480m{s}^{-1} \end{gathered}$$

Hence, correct option is C