The goal of our project was to build a trebuchet and then alter it until we achieved the maximum firing distance possible with our trebuchet. Some challenges we faced were that the size of our trebuchet could only be one meter in distance in any direction. Another restriction we faced was the type of materials available to us. We were restricted to various forms of wood and screws to connect the pieces.
My groups design consisted of a wooden base measuring 0.32 meters x 0.14 meters x 0.04 meters. We then attached two support beams measuring 0.39 meters x 0.08 meters x 0.025 meters. Then, we drilled holes in the support beams 0.03 meters down from the top and thread a hollow metal tube with the same width of the base. Our trebuchet also had an arm measuring 0.52 meters x 0.04 meters x 0.02 meters. This firing arm had three holes drilled into it, one at the half point, one resulting in a 2:1 ratio of arm lengths, and finally one with roughly a 7.5:1 ratio. We would put the tube through the support beams and the firing arm connected all the pieces together. To fire, we had one nail on the base, and another above it, connected to the arm. These nails would have rubber bands pulled over them, creating spring potential energy that would fire a clay ball. This clay ball had a string attached to it which would be looped onto another nail on the longer side of the arm resting on the base until the trebuchet was fired. |
After our initial trebuchet was constructed, we were given time to make changes to increase our distance fired. Some of the changes we made was a slight decrease in our ball’s weight, creating the 7.5:1 ratio arm, and increasing the number of rubber bands on our trebuchet. We changed our projectile’s weight to 0.01 kilograms because testing has proved that anything lighter than 10 grams has increased air resistance while once you pass 10 grams the ball has too much inertia and takes increased force to be launched causing decreased starting velocity. After testing a range of weights, it was found that 10 grams(0.01 kilograms) has the best performance. We also changed our arms ratio to 7.5:1 because the longest arm length possible will result in the farthest distance. This is because the increased distance in the arm makes the end of the arm travel more distance in the same amount of time of a shorter arm. This increase of distance in an equal time means an increase in velocity which will result in the ball going faster and further. We increased our rubber band count as far as possible, 18 bands, because the more rubber bands you have, the more force can act on the projectile. This is true because as you increase the force of the counterweight of the trebuchet, the more force will act on the other end of the arm, flinging the projectile further. For the rubber bands, each rubber band added will increase the overall spring potential energy built up and upon release, transfer into kinetic energy of the clay ball launching it longer and longer the more spring PE is added.
Calculations:
Velocity overall: Velocity is the rate of distance covered over time in a certain direction. You can find the overall velocity using the equation √((horizontal velocity)^2+(vertical velocity)^2). The overall velocity of our launched projectile was 20.1 meters per second or 45 miles per hour
Velocity horizontal: horizontal velocity is the velocity of an object in direct relation to the horizontal distance covered and the overall time. The equation for horizontal velocity is v=horizontal distance/ time. Our horizontal velocity was 8.6 meters per second or around 19 miles per hour.
Velocity vertical: Vertical velocity is the component of overall velocity which relates to distance traveled vertically and the time it takes to reach the max height of the object. You can find vertical velocity with the equation v=vertical distance/time rising/falling. Our vertical velocity of the clay ball we launched was 18.13 meters per second or 40.5 miles per hour
Spring Potential Energy: Spring potential energy is the built up potential energy in a spring which is generated when the spring is compressed or expanded. You can find Spring PE using the equation Spring PE=½(k)(x)^2 where k is the spring constant of the spring and x is the distance displaced. The spring potential energy of our rubber bands used as a counterweight in our trebuchet was 4.4 joules.
Kinetic Energy of Projectile: Kinetic energy is the energy an object has due to motion. You can find kinetic energy using the equation KE=½ (m)v^2 where m is the mass of the object and v is its velocity. The kinetic energy of our projectile was two joules
Velocity overall: Velocity is the rate of distance covered over time in a certain direction. You can find the overall velocity using the equation √((horizontal velocity)^2+(vertical velocity)^2). The overall velocity of our launched projectile was 20.1 meters per second or 45 miles per hour
Velocity horizontal: horizontal velocity is the velocity of an object in direct relation to the horizontal distance covered and the overall time. The equation for horizontal velocity is v=horizontal distance/ time. Our horizontal velocity was 8.6 meters per second or around 19 miles per hour.
Velocity vertical: Vertical velocity is the component of overall velocity which relates to distance traveled vertically and the time it takes to reach the max height of the object. You can find vertical velocity with the equation v=vertical distance/time rising/falling. Our vertical velocity of the clay ball we launched was 18.13 meters per second or 40.5 miles per hour
Spring Potential Energy: Spring potential energy is the built up potential energy in a spring which is generated when the spring is compressed or expanded. You can find Spring PE using the equation Spring PE=½(k)(x)^2 where k is the spring constant of the spring and x is the distance displaced. The spring potential energy of our rubber bands used as a counterweight in our trebuchet was 4.4 joules.
Kinetic Energy of Projectile: Kinetic energy is the energy an object has due to motion. You can find kinetic energy using the equation KE=½ (m)v^2 where m is the mass of the object and v is its velocity. The kinetic energy of our projectile was two joules
Reflection:
After our Fire Away project, I learned many things. Some take aways that I found were time management is extremely important, and leadership creates better progress. As always, time management is a problem because it forced us to be on a tight schedule with a lot of progress needed to be completed. This was a huge problem for us because we needed to construct and fix a working trebuchet and then calculate how it works in around two weeks. To succesfully accomplish all of our project, we needed good time management and a set schedule. Also, our group lacked a good leader so we were unclear as to what direction we should drive our project. Without a group leader, we were confused as to what we should do everyday. One thing my group did extremely well in was the actual construction of our trebuchet. We only took one day to fully complete the building our trebuchet.
After our Fire Away project, I learned many things. Some take aways that I found were time management is extremely important, and leadership creates better progress. As always, time management is a problem because it forced us to be on a tight schedule with a lot of progress needed to be completed. This was a huge problem for us because we needed to construct and fix a working trebuchet and then calculate how it works in around two weeks. To succesfully accomplish all of our project, we needed good time management and a set schedule. Also, our group lacked a good leader so we were unclear as to what direction we should drive our project. Without a group leader, we were confused as to what we should do everyday. One thing my group did extremely well in was the actual construction of our trebuchet. We only took one day to fully complete the building our trebuchet.