What is the velocity of the wave created in the set up above?
A. \(750 \mathrm{~m} / \mathrm{s}\) B. \(300 \mathrm{~m} / \mathrm{s}\) C. \(100 \mathrm{~m} / \mathrm{s}\) D. \(150 \mathrm{~Hz}\)
Correct Answer: B
Explanation
\(\mathrm{F}=750 \mathrm{~Hz}, \mathrm{~L}=30 \mathrm{~cm}=0.3 \mathrm{~m}, \mathrm{v}=\) ? Since the second harmonic is recorded and the tube is a closed tube, \(\mathrm{F}=\frac{3 \mathrm{~V}}{4 \mathrm{~L}}\) Then, \begin{array}{l} 750=\frac{3 \mathrm{~V}}{4 \times 0.3} \\ V=\left(\frac{750 \times 4 \times 0.3}{3}\right) \mathrm{m} / \mathrm{s}=300 \mathrm{~m} / \mathrm{s} \end{array}