The behaviour of a wire under tensile stress may be described in terms of Young Modulus E of the material of the wire and the force per unit extension of the wire.
For a wire of length L and cross-sectional area A, hat is the relation between E and k?

Question

The behaviour of a wire under tensile stress may be described in terms of Young Modulus E of the material of the wire and the force per unit extension of the wire. 
For a wire of length L and cross-sectional area A, hat is the relation between E and k?

anonymous · Answer

a)E=A/kL
b)E=kA/L
c)E=kL/A
d)E=L/kA

anonymous · Answer

modulus = stress/strain

stress = force per unit area
strain = amount of deformation -> Young's modulus is for linear deformation so, change in length

anonymous · Answer

Okay, I know that E=stress/strain.
Stress=F/A and Strain= k/L. But I can't do beyond this.

anonymous · Answer

I mean how to eliminate F from the equation? :O

anonymous · Answer

he said E = force per unit extension = F/delta L

anonymous · Answer

$$
E=\frac{F}{A}\frac{L}{\Delta L}\
F=-k\Delta L
$$

anonymous · Answer

What is the negative sign for? :O

anonymous · Answer

oh, neglect that for now
it means, opposition

anonymous · Answer

Umm. I did not quite get how you substituted force. Can you please explain again?

anonymous · Answer

there is only one place I know where "k" comes in... the spring.

anonymous · Answer

You mean the spring constant?

anonymous · Answer

yep