A hanging magnesium wire with diameter 2.1 mm (2.1 × 10-3 m) is initially 1.15 m long. When a 104 kg mass is hung from it, the wire stretches an amount 8.46 mm. A mole of magnesium has a mass of 24 grams, and its density is 1.74 g/cm3. Find the approximate value of the effective spring stiffness of the interatomic force.

Answer :

Answer:

The approximate value of the effective spring stiffness of the inter atomic force is 11.32 N/m.

Explanation:

Given that,

Diameter of wire = 2.1 mm

Initial length = 1.15 m

Mass = 104 kg

Stretching length = 8.46 mm

Mass of mole of magnesium =24 g

Density = 1.74 g/cm³

We need to calculate the diameter of magnesium

Using formula of diameter

[tex]d=(\dfrac{V}{N})^{\frac{1}{3}}[/tex]

[tex]d=(\dfrac{\dfrac{M}{\rho}}{N})^{\frac{1}{3}}[/tex]

Put the value into the value

[tex]d=(\dfrac{\dfrac{24}{1.74}}{6.023\times10^{23}})^{\frac{1}{3}}[/tex]

[tex]d=2.83\times10^{-8}\ cm[/tex]

We need to calculate the stress

Using formula of stress

[tex]stress=\dfrac{F}{A}[/tex]

[tex]stress =\dfrac{104\times9.8}{\pi\times(1.05\times10^{-3})^2}[/tex]

[tex]stress =294259805.89\ N/m^2[/tex]

[tex]stress =2.94\times10^{8}\ N/m^2[/tex]

We need to calculate the strain

Using formula of strain

[tex]strain=\dfrac{\Delta l}{l}[/tex]

[tex]strain=\dfrac{8.46}{1.15}[/tex]

[tex]strain=7.35[/tex]

We need to calculate the young modulus

Using formula of young modulus

[tex]Y=\dfrac{stress}{strain}[/tex]

[tex]Y=\dfrac{2.94\times10^{8}}{7.35\times10^{-3}}[/tex]

[tex]Y=4\times10^{10}\ N/m^2[/tex]

We need to calculate the approximate value of the effective spring stiffness of the inter atomic force

Using formula of effective spring stiffness

[tex]Y=\dfrac{k}{d}[/tex]

[tex]k=Y\times d[/tex]

Put the value into the formula

[tex]k=4\times10^{10}\times2.83\times10^{-8}\times10^{-2}[/tex]

[tex]k=11.32\ N/m[/tex]

Hence,  The approximate value of the effective spring stiffness of the inter atomic force is 11.32 N/m.

The effective spring stiffness on the wire is 11.32 N/m.

How do you calculate the effective spring stiffness?

Given that the initial length of the wire is 1.15 m, stretched length is 8.46 m and the diameter of the wire is 2.1 mm.

A mole of magnesium has a mass of 24 grams, and its density is 1.74 g/cm3. Mass on the wire is 104 kg.

The diameter of the magnesium is calculated as given below.

[tex]d_m = (\dfrac {V}{N})^{\dfrac {1}{3}}[/tex]

Where N = number of molecules in one gram-mole = 6.022 × 10^23.

V is the volume which can be written as,

[tex]V = \dfrac {M}{\rho }[/tex]

Where M is the mass of mole and [tex]\rho[/tex] is the density.

Substituting the values, we get the diameter of the magnesium.

[tex]d_m =( \dfrac {\dfrac {M}{\rho}}{N})^{\dfrac{1}{3}[/tex]

[tex]d_m = (\dfrac {\dfrac {24}{1.74}}{6.022\times 10^{23}})^{\dfrac{1}{3}[/tex]

[tex]d_m = 2.83\times 10^{-8}\;\rm cm[/tex]

The stress on the wire is calculated as given below.

[tex]\tau = \dfrac {F}{A} = \dfrac {mg}{\pi r^2}[/tex]

Where F is the force, A is the cross-sectional area of the wire, m is the mass on the wire, g is the gravitational acceleration and r is the radius of the wire.

[tex]\tau = \dfrac {104\times 9.8}{3.14\times (1.05\times 10^{-3})^2}[/tex]

[tex]\tau = 2.94\times 10^8 \;\rm N/m^2[/tex]

The strain on the wire is calculated as given below.

[tex]\varepsilon = \dfrac {\Delta l}{l}[/tex]

Where [tex]\Delta l[/tex] is the stretched length of the wire and l is the normal length of the wire.

[tex]\varepsilon = \dfrac {8.46}{1.15}[/tex]

[tex]\varepsilon = 7.35\;\rm mm[/tex]

The elastic modulus on the wire is calculated by young's modulus formula.

[tex]E = \dfrac {\tau}{\varepsilon}[/tex]

[tex]E = \dfrac {2.94\times 10^8}{7.35\times 10^{-3}}[/tex]

[tex]E = 4\times 10^{10}\;\rm N/m^2[/tex]

The effective spring stiffness on the wire is calculated as given below.

[tex]E = \dfrac {k}{d}[/tex]

[tex]4\times 10^{10}=\dfrac {k}{2.83\times 10^{-8}\times 10^{-2}}[/tex]

[tex]k = 11.32 \;\rm N/m[/tex]

Hence we can conclude that the effective spring stiffness on the wire is 11.32 N/m.

To know more about stress and strain, follow the link given below.

https://brainly.com/question/8043545.