For our project, our goal was to build a catapult or a trebuchet and launch a ball as far as we could. Due to the materials we were given and had to used, we had restrictions when we built the catapult. Every time we tested the catapult, it got weaker and weaker, until finally a piece cracked. After this, we decided to go the trebuchet route which we were very happy with our end result.
At first our group made a catapult instead or a trebuchet. Our catapult got some distance but not as much as other groups that had made the trebuchet, and we didn't know what the problem was. The main problem was that we put a stopper on the top and we put it to close on the top. This made the arm be stopped at to low of an angle making the ball bee released straight. and goes to the ground. Also the stopper was taking an absolute beating, after too many times testing and to many rubber bands, a piece that was holding the stopper at the bottom cracked. After this had happened we decided to change some things. We put on a nail with no head so the ball could more easily launch off. This replaced the basket. We changed the mass of the ball to 10 grams and attached a 40 cm string on it. We also took off the stopper. The last thing was putting another hole on the arm which changed the arm ratio 2:1. After all these changes, our ball was launched max 40 meters.
Our whole class was given an assignment to design and construct a catapult or trebuchet and to launch a ball with it. Then our group was assigned to find the ideal amount of rubber bands for our catapult. Later when we tested it multiple times and gathered all the data, we found that the more rubber bands you used created larger spring potential energy. The more of this spring Potential energy gathered from the rubber band launched the ball the furthest. However for our catapult there was a limit. Since we didn't use that strong of materials when we used 18 rubber bands, after we launched it we noticed that our catapult started to fall apart [the wood was cracking]. Therefore if we use more than 18 our whole catapult could break. All in all there wasn't an exact ideal number of rubber bands, but the more rubber bands you have on your catapult, the further the ball would be launched.
Calculations
Velocity overall: The rate of distance covered over time in a certain direction. To find this you can use the equation (square root of horizontal velocity)^2+(vertical velocity)^2. The overall velocity of our launched projectile was 20.1 meters per second of 45 miles per hour.
Velocity horizontal: Velocity of an object in direct relation to the horizontal distance covered and overall time. The equation for this 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 similar to overall velocity, its the time it takes to reach the max height of an object.You find gfind this with the equation V=vertical/distance rising/falling. The Vertical velocity for our clay ball that we launched was 18.3 meters per second or 40.5 miles per hour.
Spring Potential Energy: The Spring Potential Energy is the built up potential energy in a spring which can be generated when it is either compressed or expanded. You can use Potential Energy when given the equation Spring PE=½(k)(x)^2. The spring constant is k and x is the distance placed. 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 of an object has due to motion. You can find Kinetic energy using the equation KE=½(m)v^2. M is the mass of the object and v is its velocity. The kinetic energy of our projectile was 2 joules.
My Group and I put a lot of work into this project, We accomplishhed a lot and were very happy with our final product. We made two differnt type prototypes. The first one the Catapult, worked but it wasnt the best and was putting a beating on the whole structure. The trebuchet worked way better and was super smooth. I did a lot of the building for both of the prototypes but not as much work in the data. I really enjoyed working with this group and i was very happy with what we accomplished. Two peaks that my grroup had was we were really good in building to gther, we were able to build the ctapult in 1 day. Also our groups colaberation was very good too. Two pits that we had were time managment and my leadership wasnt the best.