Question

A uniform rope of length $20m$ and mass $5kg$ is hanging vertically from a rigid support. A block of mass $4kg$ is attached to the free end. The wave length of the transverse wave pulse at the lower end of the rope is $0.04m$. The wavelength of the same pulse as it reaches the top is

• A. $0.06m$
• B. $0.12m$
• C. $1.5m$
• D. $2.2m$

Answer 1

Answer: (A)

$0.06m$

Tension at lower end is $4kg$ and at top end is $9kg$
$\therefore \frac{f_1}{f_2}=\sqrt{\frac{T_1}{T_2}}=\frac{2}{3}=\frac{{\lambda }_2}{{\lambda }_1}$
$\therefore {\lambda }_2=\frac{3}{2}\times 0.04=0.06m$