A large mirror is hung from a nail. The supporting ?

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The discussion revolves around a physics homework problem involving a large mirror hung from a nail, with specific parameters like the mirror's mass and the dimensions of the supporting wire. The user is attempting to calculate the distance between the nail and the top of the mirror's frame using a specific formula but believes their calculation is incorrect. They express uncertainty about the formula's derivation, indicating they received assistance from a friend. The community member responding welcomes the user and requests clarification on the formula's origin to provide better guidance. Accurate understanding and application of the relevant physics concepts are crucial for solving the problem correctly.
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This is the last problem of my weekly physics homework and I'm having trouble

A large mirror is hung from a nail. The supporting steel wire has a diameter of 0.20 mm and an unstretched length of 1.70 m. The distance between the points of support at the top of the mirror's frame is 1.40 m. The mass of the mirror is 30.0 kg.

What is the distance between the nail and the top of the frame when the mirror is hung?

Homework Equations


Formula I am using
mgL^3/2pir^2Y(L^2-a^2)




The Attempt at a Solution


(30kg)(9.81m/s^2)(0.85)^3/ 2pi(0.0001)^2(2e11)[(0.85^2) - (0.70^2]

= 0.06186

This is wrong
 
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Hi, and welcome to PF!

Can you explain how you arrived at the formula that you are using?
 
I really don't know but I got help from a friend. Thanks anyways.
 

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