Trebuchet & Alternative Car
Trebuchet:
For this project we built a smaller version of a medieval catapult like structure, called a trebuchet, powered by rubber bands.
For this project we built a smaller version of a medieval catapult like structure, called a trebuchet, powered by rubber bands.
Alternative Car:
In this project we built a car that was powered by stretched rubber bands in order to run on its one while using elestic potential energy.
The following pdf is the slide my group put together.
pdf.pdf | |
File Size: | 1292 kb |
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Our Project:
For the trebuchet project, we had to complete the task of launching a projectile at least 5 meters using a contraption within the frame of 1 meter. My teammates Tyler Leighton, Chris Griggy and I decided to make the trebuchet tall and narrow so that the projectile would not drag and would have a straighter flight path. Even still our machine would not launch the projectile very far, so we experimented with the mass of the projectile. Through this, we found that 10 gram clay balls were the most effective because they were fairly light and were very malleable. Other groups conducted these experiments as well. We decided to use their findings and apply them to our machine. Our findings and the findings of others allowed us to launch our projectile a maximum of 15 meters in 3 seconds.
For the alternative car project, we were given the assignment of creating a mode of transport to carry 100 pennies (250 grams) as close as possible to 5 meters. My teammates and I decided to use rubber bands to power our vehicle. We attached the rubber bands to axles using screws. By winding the wheels back the car would accelerate forward. In order to make our car go a longer distance, we added rubber bands to the back wheels to stop wobble and increase traction. With these new modifications, our car reached 4 meters in 5 seconds.
Physics Terms:
- Distance vs. Time: The comparison of the rate of change of distance traveled and time passed; d vs. t; use a graph to find slope.
- Velocity: The rate of covered distance in a direction; v=d/t; divide time by distance.
- Spring Potential Energy: The energy stored by stretching or compressing rubber bands; PEspring=1/2kx*2; multiply one half of the spring constant by the distance the spring has stretched squared.
- Gravitational Potential energy: The energy an object has due to its position at a a height or in a gravitational field; PEg=mgh; multiply the mass of the object by the height of release and by the acceleration due to gravity.
- Kinetic Energy: The energy due to motion; KE=1/2mv*2; kinetic energy is found when you multiply on half of the object's mass by the velocity squared.
- Thermal Energy: The energy converted to heat; TE=Total E-PE-KE; thermal energy is found when you subtract the PE and KE from Total energy.
- Friction: The force opposing the direction of motion due to roughness at the molecular level.
Reflection:
During the time I spent with my teammates we completed two projects together. We did fairly well on both, this was partly due to our effectiveness as a group. At one point during the alternative car project all three of us worked on separate components in order to finish it just before presenting. However, this moment highlights our lack of time management. We had several detours during the early stages, causing us to fall behind. An example of this is when our trebuchet would not fire, so when other groups were testing we were still tinkering with the design. To combat this lack of organization we became skilled at addressing problems quickly. An example of which happened on the presentation day of our car where we found that one of the tires on our car was loose, causing it to stop early. This would not have happened however if we developed a better design originally. We had amazing and extravagant ideas however they were not ideal which lead us to believe an area of improvement of ours was determining realistic solutions. An idea I had contributed was using a belt fed operation to run the rubber band through the car, we had to drop it however, because we did not have the resources or the time to complete it. Our team was behind on schedule and unrealistic often but by working well as a team and addressing problems well, we succeeded in our endeavors.