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Rube-Goldberg Catapult. Team members: Rob Burgin Craig Bowers Aaron Shannon James Hartsig. Overview. A three step Rube-Goldberg device with the purpose of shooting a ball via catapult The first step involves a ball traveling down a PVC pipe triggering a mouse trap upon landing
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Rube-Goldberg Catapult • Team members: • Rob Burgin • Craig Bowers • Aaron Shannon • James Hartsig
Overview • A three step Rube-Goldberg device with the purpose of shooting a ball via catapult • The first step involves a ball traveling down a PVC pipe triggering a mouse trap upon landing • In the next step, the mouse trap pulls the firing pin out of the catapult • The last step involves the firing of the catapult
Energy Conversions • The first step involves a ball with gravitational potential energy ( Ugrav =mgh ) which gives us (0.25 kg)(9.81 m/s/s)(0.1588 m) = 0.0389 Joules to trigger the mouse trap. • The mouse trap exerts elastic potential energy ( Fd = E ) which gives us (136 N)(0.08m) = 10.88 Joules which then converted to kinetic energy. The force required to pull the catapult pin is 1.5 N. • Since the catapult uses springs, the energy requires a spring constant. The spring constant, K, can be calculated by measuring the force per length deflection from the neutral position. A force of 34.5 N is required to obtain a deflection of .292 M.K is then equal to (34.5 N)/(.292 M)= 118 N/M for each spring. The elastic potential energy can be derived from this using ( ½ Kx2 ) multiplied by two (springs) which gives us 118N/M(.292M)2=10.06 Joules. • All potential energy used in this device converts to kinetic energy.
Conclusion • The device is very simple and reliable • The most difficult part was accounting for energy lost during the process • The calculations were very straight forward when nonconservative forces are emitted • We feel that no changes are necessary