These past weeks have been very fun building a catapult like object, called a trebuchet. We have gone from struggle to success. At first our trebuchet was firing backwards but then we modified it to fire farther than almost any other. We did this by focusing on how one specific variable changes the whole machine.
For the design of our trebuchet we had a smaller base originally but then attached that smaller base to a longer and wider base. The power to fire came from four two link rubber bands, and one spring. The firing arm was 57 cm and longer on the firing side of the trebuchet. The axle was 30 cm high in order to get the firing arm to its full power. The dowel that the firing arm was on was 1 cm wide and the legs were 12 cm.
During this process we made eight modifications. We changed how big the base was so the energy did not make the trebuchet fall over and lose energy. we changed the angle of the nail that the projectile launched from in order to help get the right release angle. we changed how many rubber bands the trebuchet had in order to get the perfect amount of power, so it did not have to much or too little power. We changed the position of the rubber bands so that the trebuchet would help whip the projectile farther. We changed the releasing screw to a nail so that there would be no grooves and it would release easier. We changed the weight of the projectile so that it was not too light or too heavy to get the most momentum and to be released at the best angle.we made the string length longer so that the projectile could be shot farther, and we added a spring to help with the rubber bands.
Clear paragraph.
On our trebuchet the nail that releases the projectile, helps the projectile travel farther when it is bent at a sixty degree angle. We had a series of tests to find which degree degree angle worked the best. Seventy degrees made the projectile go nine meters, ninety degrees made the projectile go 3.3 meters, and sixty degrees made the projectile go 9.8 meters. When the the trebuchet is launched the projectile goes the farthest when the nail is at a sixty degree angle facing forward. This is because when the trebuchet is launched the nail holds on to the projectile for just the right amount of time. When the nail was a sixty degree angle it made the projectile release at a forty five degree angle which helps most objects get launched farther.
- The mass of our projectile was 0.011 kg
- The horizontal distance was 38 meters
- The vertical distance was 9.6 meters
- The projectile was in the air for 9.5 seconds
- The horizontal velocity was 13.72 meters per second
- The spring constant was 5.25 newtons
- The initial spring velocity was 21.875 Jules
- The kinetic energy was 1.94 Jules
- The total energy converted was 5%
The trait that makes our design so good was the nail releases point and the rubber bands. We kept on adjusting the angle of the nail to make sure the projectile realised at the best point. We kept trying different sizes and amounts of rubber bands until we found the most efficient way. We had four pairs of rubber bands (each pair was attached) to get the most energy.
Overall this project was one of the most fun we have done so far and my group and I learned lots from it. We learned how to work better as a team by incorporating everyone's ideas and when we had to step it up.