Câu hỏi 27

ta có

\(\begin{array}{l}
f = 400 \pm 10Hz\\
\lambda = 82,5 \pm 1,0cm\\
v = \lambda .f = > \overline v = \overline \lambda .\overline f = 82,5.400 = 33000cm/s = 330m/s
\end{array}\)

 δv=δλ+δf

\(\begin{array}{l}
\Rightarrow \frac{{\Delta v}}{v} = \frac{{\Delta f}}{f} + \frac{{\Delta \lambda }}{\lambda } = \frac{1}{{82,5}} + \frac{{10}}{{400}} = 0,037\\
= > \Delta v = 0,037.330 = 12m/s\\
= > v = 330 \pm 12m/s
\end{array}\)