Question

The flow limit of commercial-grade aluminum is given as σ = 120 MPa, the modulus of elasticity is E = 70 GPa and the density is 2.7 gr / cm3.
a) There is a 4mm diameter and 3m long wire which made with this material. How many N should be applied to make this wire 3mm longer?
b) If a 4 mm diameter wire made of this material is hung from the ceiling, what should be the total length of the wire to carry its own weight without plastic deformation?

just please step-by-step because it's too important for me. thanku so muc

Answer 1

Given:

stress, σ = 120 MPa= 120N/mm2

Modulus of elasticity , E = 70 GPa =70X103 N/mm2

Density = 2.7 gr / cm3= 2.7X10-6 kg/mm3

Diameter, d= 4mm

for part (a) length, L= 3m=3000mm

elongation in length L= mm

find out: load applied=P in newton(N)

part (b) find out: length(L)