Physics - Wave on String Question with Solution | TestHub

Pulse speed on the rod: $v=\sqrt{\frac{T}{\mu }}$, $\mu =\frac{m}{\ell }$; travel time $t=\int \frac{dx}{v}$.

With force F at one end, the tension at distance x from the far end is $T=\frac{Fx}{\ell }$, so $t={\int }_0^{\ell }\sqrt{\frac{m}{Fx}}dx=2\sqrt{\frac{m\ell }{F}}$.

(III) $m=7$ kg, $\ell =14$ m, $F=2$ N: $t=2\sqrt{\frac{7\times 14}{2}}=14$ s -> S

Applying the same integration to each figure: I -> R (8 s), II -> P (12 s), IV -> Q (20 s).

Correct option: (C)