高校物理 波動 ~ 音

音速 (sound velocity)

$$
V = 331.5 + 0.6 t
$$
V = 331.5 + 0.6 t

うなり (beat)

$$
N = |f_1 – f_2|
$$
N = |f_1 – f_2|

弦の固有振動

\begin{eqnarray*}
\lambda _m &=& \frac{2L}{m} \\
\\
f_m &=& \frac{v}{\lambda _m} = \frac{mv}{2L}
\end{eqnarray*}
\lambda _m &=& \frac{2L}{m}

f_m &=& \frac{v}{\lambda _m} = \frac{mv}{2L}

閉管の固有振動

\begin{eqnarray*}
\lambda _m &=& \frac{4L}{2m – 1} \\
\\
f_m &=& \frac{V}{\lambda _m} = \frac{(2m – 1)}{4L}
\end{eqnarray*}
\lambda _m &=& \frac{4L}{2m – 1}

f_m &=& \frac{V}{\lambda _m} = \frac{(2m – 1)}{4L}

開管の固有振動

\begin{eqnarray*}
\lambda _m &=& \frac{2L}{m} \\
\\
f_m &=& \frac{V}{\lambda _m} = \frac{mV}{2L}
\end{eqnarray*}
\lambda _m &=& \frac{2L}{m}

f_m &=& \frac{V}{\lambda _m} = \frac{mV}{2L}

ドップラー効果 (Doppler effect)

$$
f_\text{o} = \frac{V – v_\text{o}}{V – v_\text{s}} f_\text{s}
$$
f_\text{o} = \frac{V – v_\text{o}}{V – v_\text{s}} f_\text{s}