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## Homework Statement

The length of a unstressed girder is found to be 1.2m at a temp of 20 oC. A tensile load is then applied and some time later the temp is 50 oC and the length of the girder 1.202m evaluate:

(a) the tensile stress due to the applied load in the girder.

(b) the factor of safety that is in operation if the UTS for the girder is 550MN/m2

(c) the strain and hence the change in length of the girder, if the temp remains at 20 oC

E = 200 GN/m2 coefficient of linear expansion = 12 x 10 - 6

## Homework Equations

X = length x coefficient of linear expansion x change in temp

strain = coefficent of linear expansion x change in temp

stress = modulus of elasticity x coefficient of linear expansion x change in temp

stress = U.T.S/ F.S

## The Attempt at a Solution

(a) stress = 200 x 10 9 x 12 x 10 - 6 x 30 oC ( this is from 50 oC- 20 oC = 30 oC)

= 72 MN/m2

(b) f.s = u.t.s/stress

550 x 10 6 / 72 x 10 6 = 7.63

(c) strain = coefficient of linear expansion x change in temp

12 x 10 -6 x 20 oC = 0.24 x 10 -3

if someone would be so kind to tell me if this correct it will be much appreciated.