Question

Calculate the velocity of sound in the gas, if waves of wavelength $1m$ and $1.01m$ produce $12$ beats in $3$ seconds :

• A. $320m/sec$
• B. $404m/sec$
• C. $340m/sec$
• D. $350m/sec$

Answer 1

Answer: (B)

$404m/sec$

$v=\lambda \times \nu$

${\nu }_1=\frac{v}{{\lambda }_1}=\frac{v}{1}$ ......(1)

${\nu }_2=\frac{v}{{\lambda }_2}=\frac{v}{1.01}$ .......(2)

Given

${\nu }_1-{\nu }_2=\frac{12}{3}=4$

$\therefore {\nu }_1-{\nu }_2=4=v\ast \frac{1.01-1}{1.01}$

$\Rightarrow v=404m/s$