EGR 105 Foundations of Engineering I Fall 2007 – Week 3

EGR105 – Week 3 Topics Project Description Graphing with Excel Assignment # 3

Bungee Jumping Project Project goal is to demonstrate that a proper combination of physics, math, and engineering can successfully yield a predictable and safe jump design. Specifically, your team is to combine theory with experimental measurements to design, build, and test a small-scale model of a bungee jump.

Initially When Jumper is at Top Potential energy only is present center of gravity of the jumper W = mg h

During Free Fall Fall distance d, 0 ≤ d ≤ L Some potential energy is converted to kinetic, so v = velocity d

During Cord Stretching Now the cord starts to store energy since d > L Energy stored in cord equals the integral of the cord force F d stretch = d – L original cord length L (without stretch)

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! (next week) v = 0 d0d0 L

Typical Models for Cords Linear Model (Hooke’s Law): More Realistic Nonlinear Model Cubic Model: Stretch s Force F(s) Linear Cubic

Excel Plotting Techniques Enter or Calculate Data – Typically In Columns Then Employ Chart Wizard Plotting and Excel’s terminology: –“Chart” (use XY scatter, not line!!) –“Category” is the independent variable, horizontal axis, abscissa –“Value” is the dependent variable, vertical axis, ordinate Live demo in a few minutes

Assignment # 3 Excel plotting assignment Separate worksheet for each problem Keep graphs on same sheet with data Save as lastname_3.xls to me as an attachment (Office 2003 file format – Please)