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 -6x2 + 222.5x4 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?