Q. A string of density 7.5 gm $cm^{- 3}$ and area of cross-section 0.2$mm^{2}$ is stretched under a tension of 20N. when it is plucked at the mid-point, the speed of the transverse wave on the wire is
A) $116ms^{- 1}$
B) $40\ ms^{- 1}$
C) $200\ ms^{- 1}$
D) $80\ ms^{- 1}$
Explanation
(a) The speed of transverse wave
$v = \sqrt{\frac{T}{m}}$
Given, T=20N,
$\frac{M}{\iota} = \frac{d \times A\iota}{\iota} = d \times A\ \ \ $
$\therefore = \sqrt{\frac{20 \times 10^{- 3}}{7.5 \times 0.2 \times \left( 10^{- 3} \right)^{2}}}$
$v \approx 116ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.