Consider a spring that does not obey Hooke's law very faithfully. One end of the spring is fixed. To keep the spring stretched or compressed an amount x, a force along the x-axis with x-component Fx=kx−bx2+cx3 must be applied to the free end. Here k=100N/m, b=700N/m2, and c=12000N/m3. Note that x>0 when the spring is stretched and x<0 when it is compressed.

Respuesta :

Answer:

The work done will be 0.115 J.

Explanation:

Given that,

[tex]k=100\ N/m[/tex]

[tex]b=700\ N/m^2[/tex]

[tex]c=12000\ N/m^3[/tex]

A force along the x-axis with x-component,

[tex]F(x)=kx-bx^2+cx^3[/tex]

Suppose, How much work must be done to stretch this spring by 0.050 m from its unstretched length?

We need to calculate the work done

Using formula of work done

[tex]W(x)=\int{F(x)dx}[/tex]

Put the value into the formula

[tex]W(x)=\int{(kx-bx^2+cx^3)dx}[/tex]

[tex]W(x)=\dfrac{kx^2}{2}-\dfrac{bx^3}{3}+\dfrac{cx^4}{4}[/tex]

Put the value of k,b,c and x

[tex]W(0.050)=\dfrac{100\times(0.050)^2}{2}-\dfrac{700\times(0.050)^3}{3}+\dfrac{12000\times(0.050)^4}{4}[/tex]

[tex]W(0.050)=0.115\ J[/tex]

Hence, The work done will be 0.115 J.

The value of spring displacement is greater than zero. Therefore, spring is stretched.

Force in spring :

  It is given as,  [tex]F=kx[/tex]

Where k is constant and x is amount of displacement.

The force function is given that,

       [tex]F(x)=kx-bx^{2}+cx^{3}[/tex]

Here given that,  [tex]k=100N/m, b=700N/m^{2} , c=12000N/m^{3} .[/tex]

Substitute all values in above equation,

           [tex]F(x)=100x-700x^{2} +12000x^{3}[/tex]

To check, the spring is stretched or it is compressed.

Substitute f(x) = 0

          We get x is greater than zero.

Thus, The value of spring displacement is greater than zero. Therefore, spring is stretched.

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