Answer:
The length of the string is 0.051 meters
Step-by-step explanation:
It is given that,
Tension in the string, T = 240 N
Mass of the string, m = 0.086 kg
Speed of the wave, v = 12 m/s
The speed of the wave on the string is given by :
![v=\sqrt{(T)/(M)}](https://img.qammunity.org/2020/formulas/physics/college/7t2u16csokuwyeye6omyno80pf2rklf5mn.png)
M is the mass per unit length of the string i.e. M = m/l.......(1)
So,
![M=(T)/(v^2)](https://img.qammunity.org/2020/formulas/physics/college/punerecbobd7q0ky8lu5t5ufu5u5gr4fzi.png)
![M=(240\ N)/((12\ m/s)^2)](https://img.qammunity.org/2020/formulas/physics/college/b3i34gh7zer4igrnmu14yq7e0u9mpxn81g.png)
M = 1.67 kg/m
The length of the string can be calculated using equation (1) :
![l=(m)/(M)](https://img.qammunity.org/2020/formulas/physics/college/8odyp4y3j294txk8icj7wc0g3riobjfi04.png)
![l=(0.086\ kg)/(1.67\ kg/m)](https://img.qammunity.org/2020/formulas/physics/college/6x5ek4oi1km0z4ovju80iodlh1g8zmg1vu.png)
l = 0.051 m
So, the length of the string is 0.051 meters. Hence, this is the required solution.