An aluminium wire 3m long and of uniform circular cross-sectional area is stretched 6mm by the application ..?

Question

of a tensile load of 2.5kN.

Calculate the wire diameter if the modulus of elasticity of the wire material is known to be 70GPa?

Please show full working out!!!

Answer 1

waaaahhhh?? try to make sense PLZ .. for the sake of ALL OF us  

Answer 2

Need to know the diameter or cross sectional area first. You do not need the tensile load or the elasticity.

But if I assume a diameter d, then the volume of the wire is

  V = πr²h

  V = π(d/2)²3

After stretching:

new length is 3.006 meter

volume stays the same

what is new diameter, call it D?

V = π(d/2)²3 = π(D/2)²(3.006)

(d)²3 = (D)²(3.006)

(d/D)² = 3.006/3 = 1.002

d/D = 1.001

So the diameter is decreased by 0.1% from what it was.

edit: corrected arith mistake.

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