Solving Hooke's Law Problem: Find Delta l

[lorik]

Homework Statement

In a pole with dimension lo=5m and section S=20 cm square acts the force of F=20Kn vertically
downwards . How long will it go downwards, ---- thus delta l is needed

Homework Equations

I have delta l /lo =1/ EY *F/S

The Attempt at a Solution

I know the solution is giving me only delta l = 0.25 mm

how do i get delta l from above formula and what about EY which isn't needed ?

Could this be correct delta l = lo/ey * F/s ?

 

[radou]

Does the force act along the "direction of the pole"? And aren't you given any value for E?

 

[lorik]

Does the force act along the "direction of the pole"? And aren't you given any value for E?

Yes it does . Like its written in the book I see E is not given any number ! that's yungs module btw.

 

[radou]

If this is the correct statement of the problem, then I don't see how to calculate the elongation without Young's modulus.

 

[lorik]

Your correct thanks for help