Question

A wave pulse is travelling on a string of linear mass density $6.4\times 10^{- 3} \, kg \, m^{- 1}$ under a load of $80 \, kgf$ . Calculate the time taken by the pulse to traverse the string, if its length is $0.7 \, m$

• A. $2\times 10^{- 3}s$
• B. $3\times 10^{- 3} \, s$
• C. $4\times 10^{- 2} \, s$
• D. $5\times 10^{2}s$

Answer 1

Answer: (A)

Here, $\text{T = 80}$ kgf = $\text{= 80 }\times \text{ 9}\text{.8 }$ N ;
$m = 6.4 \times 10^{- 3}$ kg m^-1
$Now, \upsilon = \sqrt{\frac{\text{T}}{\text{m}}} = \sqrt{\frac{8 0 \times 9 \cdot 8}{6 \cdot 4 \times 1 0^{- 3}}} = 3 5 0 \text{m } \text{s}^{-1}$
Therefore, time taken by the wave pulse to traverse 0.7 m length of the string,
$t = \frac{ l }{\upsilon} = \frac{\text{0} \text{.} 7}{3 5 0} = 2 \times 1 0^{- 3}$ s