EF151 Final Engineering Team EF151 Final Engineering Team Project:Project:

Austin EldridgeAustin Eldridge

Armand MendezArmand Mendez

Jack HuntleyJack Huntley

Erica HawkinsErica Hawkins

The Plexi-TrapThe Plexi-Trap

Design Design OverviewOverview

Ball Starts by rolling around rampActivates First Mouse trap which fires marble through tubeMarble hits Second Mouse trap which drops paper

Paper hits final trap that delivers the stamp

Equation Equation OverviewOverview

Gravitational Potential Energy Kinetic Energy

Conservation of Momentum

Trajectory Equation

Ball rolling down ramp(.000373slugs)(32.3ft/s/s)(.812ft) = ½ (.000373slugs)v^2v = 7.23 ft/s

Marble being fired from tube(0ft -0.146ft) = (1.08ft - 0 ft)tan(45°) - (32.3ft/s/s) / (2v^2) (1 + tan(45°)^2) (1.08ft - 0ft)^2v = 5.53 ft/s

Swing arm hitting marble(.000248slugs)(0 ft/s) + (.000496slugs)(v) = (.000248slugs)(5.53 ft/s) + (.000496 slugs)(0 ft/s)v = 2.77 ft/s

Design/Construction Design/Construction IssuesIssues

•Mouse trap spring launched marble too far

•Needed longer mouse trap levers

•Reliability of projectile

•Original tubing for ball failed due to design constraints (height limit of box) and friction/air resistance

Issue Solution•Untwist spring to lower its k value

•Solder wire onto existing levers and extend them

•Practice makes perfect!

•Replaced tubing with wooden ramps

ConclusionsConclusions Infinite Number of ways to do something inefficiently Still difficult to build something that works consistently Friction and stored energy can do a lot more than you would think it should Planning is key