Alternative Energy Vehicle
We were assigned to design an energy storage mechanism that goes exactly five meters and stops at five meters. It also needed to be portable and be able to hold two passengers (two rolls of pennies or 250 grams). My group had many different ideas on how to make this vehicle, but we decided on using rubber bands, which is spring potential energy, as our main energy source. Our original blue prints had two separate rubber band chains. However, we quickly figured out that having one rubber band chain of seven rubber bands allowed the rubber band to keep going once the rubber band unraveled all the way rather than stopping right when the bands unraveled. Our vehicle consistently when about four meters instead of five so we added a second source of energy which was gravitational energy. We put our vehicle on a ramp at 0.245 meters tall and released it. This gave it a little extra momentum to get to the five meter mark.
Content
Spring constant
k=F/d
k=10N/0.3m = 33.3
Spring potential energy
PEspring=1/2kx^2
PEspring=1/2(33.3)(0.4m)^2
PEspring=2.66J, PEspring=1.5J, PEspring=0.66J, PEspring=0.16J
Gravitational potential energy
PEg=mgh
PEg=1.305kg(9.8m/s)(0.245m)
PEg=3.13
Kinetic energy
KE=1/2mv^2
KE=1/2(1.305)(1.75)
KE=2.06, KE=1.2, KE=1.0, KE=0.75, KE=0.63
Total Energy
TE=2.6
Thermal Energy
Thermal Energy= TE-KE-PEspring
Thermal Energy=5.79-2.06-1.5
Thermal Energy=2.23, 3.93, 4.68, 5.04, 5.16, 5.79
Rotational inertia
The rubber bands rap around the 0.4m dowel 8 times. So the rubber bands start with 0.4m of stretch
Additional Information
The rubber bands fling off at 4m and it starts with 0.4m of stretch. The first meter takes 0.5 seconds, the second meter takes 0.5 seconds, the third meter takes 0.6 seconds, the fourth meter takes 0.7 seconds, and the fifth meter takes 1.1 seconds. The vehicle is 1.305kg and the vehicle starts at 0.245m high on a ramp lined up with the 0m mark.
Reflection
Overall, this project was fun to do because it had two parts. First we did a trebuchet and then we did an alternative energy vehicle. Each project had rules to oblige. For the trebuchet it had to be no higher than 1 meter, had to be able to be transported easily by one person, and should fire on its own. For the alternative energy vehicle it needed to go 5 meters by itself, be able to hold two passengers on 250 grams, and be portable. In both projects my group worked very well together and we incorporated all of our ideas into our machine. Something that I personally did well was communication and collaboration. I communicated my ideas to my teammates and we collaborated on the perfect design for our alternative energy vehicle.