1. EGR 105 Foundations of Engineering I Fall 2007 – Week 4

2. EGR105 – Week 4 Topics Project Work – Bungee Cord Characterization Work in Teams - Follow Procedures Outlined in Handout 2 - Mark Cord - Use Test Stand - Add Weights and Measure Resulting Extension - Record Data - Enter Data into Excel Spreadsheet and Do Calculations & Plots

3. From Last Lecture At the Bottom, distance d 0 Velocity v is now zero, so We could solve for d 0 if we knew F. So we need to characterize bungee cord! (this week) v = 0 d0d0 L

4. Typical Models for Cords Linear Model (Hooke’s Law): More Realistic Nonlinear Model Cubic Model: Stretch s Force F(s) Linear Cubic But You First Want to Gather Experimental Data on Your Team’s Cord

5. Bungee Cord Testing Characterization of F(s) lolo Wooden Peg Cord Loop Knot ? W - Mark Cord - Use Test Stand - Add Weights - Measure Resulting Extension - Record Data

6. Typical Data Expected Force F(s)           Most Likely Will Be Nonlinear

7. Typical Data in Excel lo =4 Weight(lb)l(l-lo)(l-lo)/lo 0400 14.40.40.1 1.444.60.60.15 25.21.20.3 2.445.71.70.425 36.32.30.575 3.446.92.90.725 47.63.60.9 58.14.11.025 68.64.61.15

8. Assignment # 4 Enter Data Into Excel Spreadsheet Calculate Δs and Δs/l o Make Plot of F versus Δs/l o Keep Plot on Same Page as Data Save as teamnumber_4.xls Turn in hard copy Due October 4