Lab 2 Report ENGR 103/123- 2. Calculations/Theoretical Predictions - Potential Energy of the Spring a) Determine the Spring Constant 2 of 6 Using the fish scales provided, record the amount of force (in units of lbf) that is required to displace the spring for multiple lengths. For example, record the force to compress the spring by 0.2", then again at 0.4", etc. Use five different lengths when recording the forces. This has been done for you below. Using Excel, plot a Force vs Displacement graph for the spring in your Nerf toy. Add a linear trend line to the graph, also displaying the equation and the R values on the graph. Label the graph according to chapter 9.3 in your text. Print out and attach this graph at the end of this handout. You are required to have an R value greater than 0.95. If your data does not meet this standard, repeat the testing and replot your data. You are only required to perform as many attempts as is necessary to meet this requirement. Raw Data: Attempt 1 Attempt 2 Attempt 3 Displacement (in) Force (lbf) Displacement (in) Force (lbf) Displacement (in) Force (lbf) 0.20 3.10 0.40 4.03 0.60 4.69 0.80 5.57 1.0 (max displacement) R= 6.37 R = R= Based on your graph, the spring constant (the derivative of your graph) for your spring is: Lab 2 Report ENGR 103/123- b) Calculate the usable potential energy stored in spring lbf/in 3 of 6 To calculate the useable potential energy in the spring, graphically find the integral of the curve plotted in Excel. Note: You cannot assume a point of (0 in, 0 lbf) when solving for the area. Explain the reason for this below.