Answer:
The tension in the string is [tex]T = 1.49*10^{-6}N[/tex].
Explanation:
For a string with tension [tex]T[/tex] and linear density [tex]\mu_d[/tex] carrying a transverse wave at speed [tex]v[/tex] it is true that
[tex]v = \sqrt{\dfrac{T}{\mu_d} }[/tex]
solving for [tex]T[/tex] we get:
[tex]T = \dfrac{v^2}{\mu_d}.[/tex]
Now, the transverse wave covers the distance of 7.4mm in 0.88s, which means it's speed is
[tex]v =\dfrac{7.4*10^{-3}m}{0.88s} \\\\v = 8.4*10^{-3}s[/tex]
And it's linear density (mass per unit length) is
[tex]\mu_d = \dfrac{0.35kg}{7.4*10^{-3}m} \\\\\mu_d = 47.3kg/m[/tex]
Therefore, the tension in the cord is
[tex]T = \dfrac{(8.4*10^{-3}m/s^2)^2}{47.3kg/m}.[/tex]
[tex]\boxed{T = 1.5*10^{-6}N}[/tex]
or in micro newtons
[tex]T =1.5\mu N[/tex]
