of the wire $(\mathrm{m}=\mathrm{M} / \mathrm{L})$
Let $\left.A \propto L^{a} F^{b} m^{c} \quad \text { ……….. } \quad \text { (Equation } 1\right)$
Writing the dimensions of each in the above equation, we get
$\left[\mathrm{M}^{0} \mathrm{L}^{0} \mathrm{T}^{-1}\right]=\mathrm{L}^{\mathrm{a}}\left[\mathrm{M}^{1} \mathrm{L}^{1} \mathrm{T}^{-2}\right]^{\mathrm{b}}\left[\mathrm{M}^{0} \mathrm{L}^{-1}\right]^{\mathrm{C}}$
$=M^{b+c} L^{a+b-c} T^{-2 b}$
Here, $b+c=0$
$a+b-c=0 \text { and }$
$-2 b=-1$
On solving, we get
$a=-1, b=1 / 2$ and $c=-1 / 2$
Substituting these values in equation $(1),$ we get
$A=k L^{-1} F^{1 / 2} m^{-1 / 2}$
$=k \frac{1}{L} \sqrt{\frac{F}{m}}$
or $A=k \frac{1}{L} \sqrt{\frac{F}{(M / L)}}$
or $A=k \sqrt{\frac{F}{M L}}$
Experimentally $\mathrm{k}=1 / 2$ $\therefore A=\frac{1}{2} \sqrt{\frac{F}{M L}}$
Assume that the sound of the whistle is composed of components varying in frequency from $f_1=800 \mathrm{~Hz}$ to $f_2=1120 \mathrm{~Hz}$, as shown in the figure. The spread in the frequency (highest frequency - lowest frequency) is thus $320 \mathrm{~Hz}$. The speed of sound in still air is $340 \mathrm{~m} / \mathrm{s}$.
$1.$ The speed of sound of the whistle is
$(A)$ $340 \mathrm{~m} / \mathrm{s}$ for passengers in $A$ and $310 \mathrm{~m} / \mathrm{s}$ for passengers in $B$
$(B)$ $360 \mathrm{~m} / \mathrm{s}$ for passengers in $A$ and $310 \mathrm{~m} / \mathrm{s}$ for passengers in $B$
$(C)$ $310 \mathrm{~m} / \mathrm{s}$ for passengers in $A$ and $360 \mathrm{~m} / \mathrm{s}$ for passengers in $B$
$(D)$ $340 \mathrm{~m} / \mathrm{s}$ for passengers in both the trains
$2.$ The distribution of the sound intensity of the whistle as observed by the passengers in train $\mathrm{A}$ is best represented by
$Image$
$3.$ The spread of frequency as observed by the passengers in train $B$ is
$(A)$ $310 \mathrm{~Hz}$ $(B)$ $330 \mathrm{~Hz}$ $(C)$ $350 \mathrm{~Hz}$ $(D)$ $290 \mathrm{~Hz}$
Give the answer question $1,2$ and $3.$

$(A)$ a high-pressure pulse starts traveling up the pipe, if the other end of the pipe is open.
$(B)$ a low-pressure pulse starts traveling up the pipe, if the other end of the pipe is open.
$(C)$ a low-pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.
$(D)$ a high-pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.