(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

At a certain point, when a spring is stretched near its elastic limit, the spring force satisfies the equation

F = −α x + β x3 , where α = 12 N/m and β = 890 N/m3 .

Calculate the work done by the spring when it is stretched from its equilibrium position to 0.15 m past its equilibrium.

Answer in units of mJ.

2. Relevant equations

3. The attempt at a solution

since this is a nonlinear curve i thought that the area under the curve would equal the work done by the spring at the .15 m

so i integrated and got

-6x^{2}+ 222.5x^{4}

since the spring is starting at the equilibrium position, initial position is 0 and final position is .15m so

-6(.15)^{2}+222.5(.15)^{4}= -.02235

this doesn't make sense since we are pulling the spring and the work should be positive right?

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# Calculating work done by a spring when stretched

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