Our Task
Our goal for our project was to build a trebuchet or a catapult and launch a projectile as far as we possibly could given the materials that we had. We had no restrictions on us except for the materials we were given. We kept trying and trying until we found an ending product that we were happy with. At first we decided to design a catapult instead of a trebuchet. We kept the same basic design but changed a few things along the way.
Our Design
Our design consisted of a base that measured about 0.32 meters x 0.14 meters x 0.04 meters. We also had support beams to raise the arm. These measured at 0.39 meters x 0.08 meters x 0.025 meters. We then attached a metal tube that acted as an axle for our arm to rotate around. The arm measured 0.52 meters x 0.04 meters x 0.02 meters. Our arm ratio was about 7.5:1 to start but was soon changed to a 2:1 ratio. Then, we nailed a cup to the end of the arm and were ready to launch the projectile. When we started, our catapult didn’t have much distance and we didn’t know the problem. We kept testing and testing and couldn’t figure the problem. As it turns out we had a lot of problems that we found. First, we found that the trebuchet makes it go much further than the catapult. So then we took out the basket and we put in a finishing nail and connected the ball to a 40 cm string and the ball went much further but we knew that we could get more distance out of it. Then, we changed the arm ratio to 2:1 instead of what we had before. That also made it go further but we wanted more. We then changed the mass of the ball to 10 grams or 0.01 kg. After all of these modifications we reached a maximum distance of about 40 meters. We were given a task to find the ideal conditions for a catapult or trebuchet to launch a ball. What we chose was to find the ideal amount of rubber bands that you could put on the catapult. We tested eight different amounts of rubber bands and found that more rubber bands is better. You have more spring potential energy if you have more rubber bands and the ball will then go further. There is a limit to the amount of rubber bands that you can put though. If you add too many rubber bands there is a possibility that the machine could fall apart. For example, we tried eighteen rubber bands and on that launch the cup broke and the wood began to split, so there is a limit. In conclusion there is no number of rubber bands that is ideal but if you have more rubber bands on your catapult the ball would launch farther yielding better results. Below there is a list of all of the calculations that we have done.
Physics Concepts
Overall Velocity: The overall velocity is the velocity in a certain direction. It is the distance covered over a certain time in a certain direction. To find the vertical velocity you use the equation √horizontal velocity ^2 + Vertical Velocity ^2. Our overall velocity reached 20.2 meters per second and 45 miles per hour.
Horizontal Velocity: The horizontal velocity is the distance covered horizontally in an amount of time. The equation to find this is horizontal distance/time. Our horizontal velocity was 8.6 meter per second or 19 miles per hour.
Spring Potential Energy: Spring potential energy is the energy that is built up when the spring is stretched or compressed. To find the spring potential energy you use the equation spring potential energy= F/D. F, meaning force on the spring and D, meaning the distance the spring is stretched or compressed. This was the amount of force on the rubber bands. We found the spring PE of our trebuchet to be 4.4 joules
Kinetic Energy: Kinetic Energy is the energy of an object in motion. The equation to find kinetic energy is KE=1/2mv^2. M is the mass of the object in motion, in our case the clay ball and v is the velocity of the object in motion. The spring PE is transferred over to the kinetic energy but some energy is lost in the process. We found or KE to be about 2 joules of energy.
Reflection
Over the course of this project I learned many things. In my opinion the most important thing that I learned was learning from my peers. I learned about this because we had to discuss our findings after running experiments on the ideal design of the trebuchet. At this point things weren't going very well for us. We tested the amount of rubber bands that we should put on the trebuchet. While doing this, we put too many rubber bands and the machine broke. Once we saw the resultsof the other team's experiments we decided to change the design of our trebuchet. We changed a few things for the better on our project which added a lot of distance to our launch. One thing that I would like to change is the time management. This has been the biggest issue that I have encountered in my projects thus far.
Our goal for our project was to build a trebuchet or a catapult and launch a projectile as far as we possibly could given the materials that we had. We had no restrictions on us except for the materials we were given. We kept trying and trying until we found an ending product that we were happy with. At first we decided to design a catapult instead of a trebuchet. We kept the same basic design but changed a few things along the way.
Our Design
Our design consisted of a base that measured about 0.32 meters x 0.14 meters x 0.04 meters. We also had support beams to raise the arm. These measured at 0.39 meters x 0.08 meters x 0.025 meters. We then attached a metal tube that acted as an axle for our arm to rotate around. The arm measured 0.52 meters x 0.04 meters x 0.02 meters. Our arm ratio was about 7.5:1 to start but was soon changed to a 2:1 ratio. Then, we nailed a cup to the end of the arm and were ready to launch the projectile. When we started, our catapult didn’t have much distance and we didn’t know the problem. We kept testing and testing and couldn’t figure the problem. As it turns out we had a lot of problems that we found. First, we found that the trebuchet makes it go much further than the catapult. So then we took out the basket and we put in a finishing nail and connected the ball to a 40 cm string and the ball went much further but we knew that we could get more distance out of it. Then, we changed the arm ratio to 2:1 instead of what we had before. That also made it go further but we wanted more. We then changed the mass of the ball to 10 grams or 0.01 kg. After all of these modifications we reached a maximum distance of about 40 meters. We were given a task to find the ideal conditions for a catapult or trebuchet to launch a ball. What we chose was to find the ideal amount of rubber bands that you could put on the catapult. We tested eight different amounts of rubber bands and found that more rubber bands is better. You have more spring potential energy if you have more rubber bands and the ball will then go further. There is a limit to the amount of rubber bands that you can put though. If you add too many rubber bands there is a possibility that the machine could fall apart. For example, we tried eighteen rubber bands and on that launch the cup broke and the wood began to split, so there is a limit. In conclusion there is no number of rubber bands that is ideal but if you have more rubber bands on your catapult the ball would launch farther yielding better results. Below there is a list of all of the calculations that we have done.
Physics Concepts
Overall Velocity: The overall velocity is the velocity in a certain direction. It is the distance covered over a certain time in a certain direction. To find the vertical velocity you use the equation √horizontal velocity ^2 + Vertical Velocity ^2. Our overall velocity reached 20.2 meters per second and 45 miles per hour.
Horizontal Velocity: The horizontal velocity is the distance covered horizontally in an amount of time. The equation to find this is horizontal distance/time. Our horizontal velocity was 8.6 meter per second or 19 miles per hour.
Spring Potential Energy: Spring potential energy is the energy that is built up when the spring is stretched or compressed. To find the spring potential energy you use the equation spring potential energy= F/D. F, meaning force on the spring and D, meaning the distance the spring is stretched or compressed. This was the amount of force on the rubber bands. We found the spring PE of our trebuchet to be 4.4 joules
Kinetic Energy: Kinetic Energy is the energy of an object in motion. The equation to find kinetic energy is KE=1/2mv^2. M is the mass of the object in motion, in our case the clay ball and v is the velocity of the object in motion. The spring PE is transferred over to the kinetic energy but some energy is lost in the process. We found or KE to be about 2 joules of energy.
Reflection
Over the course of this project I learned many things. In my opinion the most important thing that I learned was learning from my peers. I learned about this because we had to discuss our findings after running experiments on the ideal design of the trebuchet. At this point things weren't going very well for us. We tested the amount of rubber bands that we should put on the trebuchet. While doing this, we put too many rubber bands and the machine broke. Once we saw the resultsof the other team's experiments we decided to change the design of our trebuchet. We changed a few things for the better on our project which added a lot of distance to our launch. One thing that I would like to change is the time management. This has been the biggest issue that I have encountered in my projects thus far.