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2- Two materials, A and B, are used to make cables of
identical cross section and length, to lift identical loads.
If A has a greater Young's Modulus than B, which cable
will stretch the most when loaded? Explain why.

Answer :

Answer:

Cable  B will more stretch the most.

Explanation:

Given that,

Length of material A =[tex]l_{A}[/tex]

Length of material B =[tex]l_{B}[/tex]

If A has a greater Young's Modulus than B.

We know that,

The deflection is defined as,

[tex]\delta=\dfrac{Wl}{AE}[/tex]

For material A,

[tex]\delta_{A}=\dfrac{W_{A}l_{A}}{A_{A}E_{A}}[/tex]

[tex]\delta_{A}\propto\dfrac{1}{E_{A}}[/tex]

For material B,

[tex]\delta_{B}=\dfrac{W_{B}l_{B}}{A_{B}E_{B}}[/tex]

[tex]\delta_{B}\propto\dfrac{1}{E_{B}}[/tex]

The deflection is inversely proportional to the young's modulus.

We need to find which cable  will stretch the most when loaded

Using formula of deflection

[tex]\dfrac{\delta_{A}}{\delta_{B}}=\dfrac{\dfrac{W_{A}l_{A}}{A_{A}E_{A}}}{\dfrac{W_{B}l_{B}}{A_{B}E_{B}}}[/tex]

Put the value into the formula

[tex]\dfrac{\delta_{A}}{\delta_{B}}=\dfrac{\dfrac{Wl}{AE_{A}}}{\dfrac{Wl}{AE_{B}}}[/tex]

[tex]\dfrac{\delta_{A}}{\delta_{B}}=\dfrac{E_{B}}{E_{A}}[/tex]

So, [tex]\delta_{B}>\delta_{A}[/tex]

Hence, Cable  B will more stretch the most.

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