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A 25mm square cross-section bar of length 300mm carries an axial compressive

load of 50kN. Determine the stress set up in the bar and its change of length when the

load is applied. For the bar material E = 200 GN/m
^2​


Sagot :

Answer:

The correct answer is "299.88 mm".

Explanation:

The given values are:

Length,

[tex]l_o=300 \ mm[/tex]

Load,

[tex]P=50 \ kN[/tex]

i.e.,

   [tex]=50\times 10^3 \ N[/tex]

[tex]E=200 \ GN/m^2[/tex]

   [tex]=2\times 10^5 \ M/mm^2[/tex]

Now,

Stress,

⇒  [tex]\sigma=\frac{P}{A}[/tex]

On substituting the values, we get

⇒     [tex]=\frac{50\times 10^3}{25\times 25}[/tex]

⇒     [tex]=80 \ N/mm^2[/tex]

The change in length will be:

⇒  [tex]\Delta l=\frac{Pl}{AE}[/tex]

On substituting the values, we get

⇒       [tex]=\frac{50\times 10^3\times 300}{25\times 25\times 2\times 10^5}[/tex]

⇒       [tex]=\frac{15000\times 10^3}{1250\times 10^5}[/tex]

⇒       [tex]=0.12 \ mm[/tex]

hence,

⇒  [tex]L=l_o-\Delta l[/tex]

        [tex]=300-0.12[/tex]

        [tex]=299.88 \ mm[/tex]