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Tensile Strain

" An electricity transmission cable is composed of steel wire diameter 10mm and surrounded by six aluminium wires of diameter 10mm. The Young modulus of aluminium is 70GPa and of steel 210 GPa. The wires are tightly bounded together such that they all experience the same strain under tension. If the cable is subject to a tension of 100N what is the resultant strain?"

any help would greatly be appreciated

thank you in advance x

Reply 1

Stonebridge

A possible method. (And rushing this a bit...)
Using strain=stress/E and the fact that the strain is the same for both materials, you can say stress/E for aluminium = stress/E for steel. (Stress = force over total area for each material)
This will give you the ratio of the force on the aluminium cable to the force on the steel.
You know the sum of the forces is 100N, so you can then work out the 2 values of the forces on the two materials.
Substitute one of these back into strain=stress/E to find the strain.