For this project we made a trebuchet. The trebuchet had to fit in a 1 meter cube and so none of it's dimensions could exceed 1 meter. It shot 10 gram clay balls a very long distance.
Reflection:
I feel that one of the peaks for this project was how well our group worked together. Another peak was that our trebuchet actually shot the farthest in the class with around 55 meters. We has some low points though. In the start, my leadership wasn't great and I wasn't completely focused. Then, We also could have had more foresight with our project. I feel that sometimes we didn't have the proper organization.
Proof of Efficacy Document
For this project we had to make a trebuchet, which is a variation of a catapult. The objective for the project was to launch a small clay ball as far as possible with our trebuchet. To do this we first built our trebuchet. Then, as a class we identified 8 different variables that impacted the performance of our trebuchets. Each group then designed an single variable experiment to find out how to use this variable to maximize performance.
Our design:
Arm that pivots on axle with full range of motion, arm = 0.44m high. And the arm is around 0.5 m long. The legs are 0.46 cm high. The base is 2cm thick and is 50cm X 40cm. It includes 6 rubber bands
The rules for designing the trebuchet was that none of its dimensions could exceed one meter. The trebuchet had to have to legs that hold the axle. On the axle is the arm which pivots on the axle.
Modifications to Trebuchet:
Longer string length:
We changed our string length to around 30 cm to get more leverage for our projectile. A string longer than 30cm would drag on the ground during launch, causing energy to be lost to friction.
Release Nail Angle: Here is a CLEAR paragraph presenting my groups findings on our experiments for this variable.
Heston Wilson
Stem ¾ period
November 2, 2017
Release Nail Angle Clear Paragraph
Have you ever wanted to build a trebuchet? Well don’t forget about the release nail angle. The release nail angle is the angle of the nail that holds the string attached to the projectile in a trebuchet. In our STEM class we found that a nail release angle that is less than 90 degrees yet greater than 40 is the best for firing with a trebuchet. The length of the release nail was found to not be important. To come to this conclusion we experimented with our trebuchet with varying angles in the release nail.The trebuchet used fired a lightweight clay ball attached to a string.Our group found that our lowest distance was 7 meters when we had a angle of 40 degrees. The highest was 16.5 meters with a angle of 65 degrees. On the other end of the spectrum in our data at 90 degrees the projectile went around 11 meters. As the angle gets closer to around 60 to 70 degrees the distance the projectile goes is longer. At higher angles the projectile has a higher arc and energy is wasted going up instead of horizontally. At the lower angles the projectile hit the ground earlier and didn’t have enough time to go very far. At intermediate angles the projectile had a better balance between vertical and horizontal so it could go max distance.
In conclusion, when the release nail angle is around 60 to 70 degrees the trebuchet has the optimal trajectory to maximize distance.
Mass of Projectile:
We changed the mass of our projectile to around 10 grams. This allows minimum inertia, yet also is large enough so that the ball won’t be easily stopped by air resistance.
Stopper:
While some groups from other classes needed a stopper for their catapult, our group found that a stopper was only necessary for those who didn’t design their catapult to release the ball properly. Stoppers run the risk of damaging the arm and not allowing the arm to have a full range of motion. So we did not have a stopper.
Rubber band quantity:
Our quantity of rubber bands was around 6 which is a good number for rubber band. It was found that to many rubber bands caused the catapult to be inefficient and in some cases destroyed the projectile. Also, with lots of rubber bands it is impossible to stretch it back. Too little rubber bands
Type of projectile:
We used a clay ball, the convenient thing with the clay balls is that you can mold the string into the ball. After experimentation by another group it was found that a sphere was best for our purposes.
Rubber Band size:
We found that size 64 rubber bands were the best. They could be stretched to power the trebuchet, and they were not so small that their effect was negligible.
Not using weights: It was found that rubber bands were overall more effective for trebuchets than weights by one of the groups. The rubber bands provide more energy and more flexibility than weights. Also, more rubber bands can be put on the trebuchet.
Tech Specs:
Mass of our projectile: 10 grams or 0.01 kilograms. How much stuff our projectile has.
Horizontal Distance: 54 meters. The distance the projectile went.
Time in air: 3.7 seconds. This is how long the ball is in the air.
Vertical Distance:d= ½ at^2 9.06 meters. How high in the air the ball gets.
Horizontal Velocity: v=d/t 54m/3.7s = 14.59 how fast the object moves horizontally
Vertical Velocity = a(gravity) * t to fall. 9.8 * 1.85 = 18.13 m/s Velocity vertically.
Total velocity: The velocity in the actual direction the ball goes. Represented with the hypotenuse of a right triangle. a^2 + b^2 = c^2. Our total velocity is 29.5 m/s.
Angle of release: The angle that the projectile is released. Around 35 degrees.
Spring Constant of rubber bands: The spring constant is a constant that measures how much springiness an object has. K=F/D. The spring constant of our size 64 rubber bands is around 490
Initial Spring potential energy: the amount of energy a spring has when compressed. PEspring = 1/2 k x^2. Where x is the distance the spring has stretched. PE = ½ 490 * 0.13^2 PE = 34.3 joules.
Kinetic Energy: the energy an object has from motion. KE = ½ mv^2. Ke = 0.5 * 0.01 * 29^2. Ke = 4.2 joules.
Percent energy converted: The amount of potential energy converted to kinetic energy. Our trebuchets energy conversion rate is around 12%. Which is pretty good for trebuchets.
BUY NOW.
Our trebuchet has all sorts of amazing features!!!
Lots of potential
High energy transfer rate,
No stopper required.
BUY NOW AT YOUR LOCAL TREBUCHET STORE.
Reflection:
I feel that one of the peaks for this project was how well our group worked together. Another peak was that our trebuchet actually shot the farthest in the class with around 55 meters. We has some low points though. In the start, my leadership wasn't great and I wasn't completely focused. Then, We also could have had more foresight with our project. I feel that sometimes we didn't have the proper organization.
Proof of Efficacy Document
For this project we had to make a trebuchet, which is a variation of a catapult. The objective for the project was to launch a small clay ball as far as possible with our trebuchet. To do this we first built our trebuchet. Then, as a class we identified 8 different variables that impacted the performance of our trebuchets. Each group then designed an single variable experiment to find out how to use this variable to maximize performance.
Our design:
Arm that pivots on axle with full range of motion, arm = 0.44m high. And the arm is around 0.5 m long. The legs are 0.46 cm high. The base is 2cm thick and is 50cm X 40cm. It includes 6 rubber bands
The rules for designing the trebuchet was that none of its dimensions could exceed one meter. The trebuchet had to have to legs that hold the axle. On the axle is the arm which pivots on the axle.
Modifications to Trebuchet:
Longer string length:
We changed our string length to around 30 cm to get more leverage for our projectile. A string longer than 30cm would drag on the ground during launch, causing energy to be lost to friction.
Release Nail Angle: Here is a CLEAR paragraph presenting my groups findings on our experiments for this variable.
Heston Wilson
Stem ¾ period
November 2, 2017
Release Nail Angle Clear Paragraph
Have you ever wanted to build a trebuchet? Well don’t forget about the release nail angle. The release nail angle is the angle of the nail that holds the string attached to the projectile in a trebuchet. In our STEM class we found that a nail release angle that is less than 90 degrees yet greater than 40 is the best for firing with a trebuchet. The length of the release nail was found to not be important. To come to this conclusion we experimented with our trebuchet with varying angles in the release nail.The trebuchet used fired a lightweight clay ball attached to a string.Our group found that our lowest distance was 7 meters when we had a angle of 40 degrees. The highest was 16.5 meters with a angle of 65 degrees. On the other end of the spectrum in our data at 90 degrees the projectile went around 11 meters. As the angle gets closer to around 60 to 70 degrees the distance the projectile goes is longer. At higher angles the projectile has a higher arc and energy is wasted going up instead of horizontally. At the lower angles the projectile hit the ground earlier and didn’t have enough time to go very far. At intermediate angles the projectile had a better balance between vertical and horizontal so it could go max distance.
In conclusion, when the release nail angle is around 60 to 70 degrees the trebuchet has the optimal trajectory to maximize distance.
Mass of Projectile:
We changed the mass of our projectile to around 10 grams. This allows minimum inertia, yet also is large enough so that the ball won’t be easily stopped by air resistance.
Stopper:
While some groups from other classes needed a stopper for their catapult, our group found that a stopper was only necessary for those who didn’t design their catapult to release the ball properly. Stoppers run the risk of damaging the arm and not allowing the arm to have a full range of motion. So we did not have a stopper.
Rubber band quantity:
Our quantity of rubber bands was around 6 which is a good number for rubber band. It was found that to many rubber bands caused the catapult to be inefficient and in some cases destroyed the projectile. Also, with lots of rubber bands it is impossible to stretch it back. Too little rubber bands
Type of projectile:
We used a clay ball, the convenient thing with the clay balls is that you can mold the string into the ball. After experimentation by another group it was found that a sphere was best for our purposes.
Rubber Band size:
We found that size 64 rubber bands were the best. They could be stretched to power the trebuchet, and they were not so small that their effect was negligible.
Not using weights: It was found that rubber bands were overall more effective for trebuchets than weights by one of the groups. The rubber bands provide more energy and more flexibility than weights. Also, more rubber bands can be put on the trebuchet.
Tech Specs:
Mass of our projectile: 10 grams or 0.01 kilograms. How much stuff our projectile has.
Horizontal Distance: 54 meters. The distance the projectile went.
Time in air: 3.7 seconds. This is how long the ball is in the air.
Vertical Distance:d= ½ at^2 9.06 meters. How high in the air the ball gets.
Horizontal Velocity: v=d/t 54m/3.7s = 14.59 how fast the object moves horizontally
Vertical Velocity = a(gravity) * t to fall. 9.8 * 1.85 = 18.13 m/s Velocity vertically.
Total velocity: The velocity in the actual direction the ball goes. Represented with the hypotenuse of a right triangle. a^2 + b^2 = c^2. Our total velocity is 29.5 m/s.
Angle of release: The angle that the projectile is released. Around 35 degrees.
Spring Constant of rubber bands: The spring constant is a constant that measures how much springiness an object has. K=F/D. The spring constant of our size 64 rubber bands is around 490
Initial Spring potential energy: the amount of energy a spring has when compressed. PEspring = 1/2 k x^2. Where x is the distance the spring has stretched. PE = ½ 490 * 0.13^2 PE = 34.3 joules.
Kinetic Energy: the energy an object has from motion. KE = ½ mv^2. Ke = 0.5 * 0.01 * 29^2. Ke = 4.2 joules.
Percent energy converted: The amount of potential energy converted to kinetic energy. Our trebuchets energy conversion rate is around 12%. Which is pretty good for trebuchets.
BUY NOW.
Our trebuchet has all sorts of amazing features!!!
Lots of potential
High energy transfer rate,
No stopper required.
BUY NOW AT YOUR LOCAL TREBUCHET STORE.