Answer: 100 J
Explanation: 1/2 5 x 2^2 = 100
Hope this made any sense.
They protested by marching in the streets.
Well they could go down a hill to gain more kinetic energy.
The wavelength of the note is

. Since the speed of the wave is the speed of sound,

, the frequency of the note is

Then, we know that the frequency of a vibrating string is related to the tension T of the string and its length L by

where

is the linear mass density of our string.
Using the value of the tension, T=160 N, and the frequency we just found, we can calculate the length of the string, L: