Proof Of Efficacy
For our project we made a trebuchet. The purpose of a trebuchet is to launch a projectile, in our case a clay ball, as far as possible. Our machine has a base made out of 2 x 6 and is 57 cm long. Our arm is 80 cm long and the arm is 30 cm off the ground, which is the perfect height to allow the arm to rotate fully around the axle. Our machine achieved and maximum distance of 38 meters and went 15 meters high.
Our 8 modifications:
How to maximum distance with a trebuchet
When using a trebuchet, the less space between the arm and the legs(less wobble), the further the projectile will go. In this project, we were assigned to build a trebuchet that launches a clay ball as far as possible. The trebuchet works by applying a force downwards on one side of a lever that then launches a ball upwards on the other side. We tested if having wobble on the lever would affect how far the ball goes. We found that the arm with 0.5 cm of wobble went and average of 14 meters. The ball with 3.5 cm of wobble went an average of 11.8. This means that the ball went about 2 meters farther with the less wobble. That means if you are building a trebuchet make sure to have as little of wobble as possible on the lever to maximum distance.
Technical Specifications
Why buy this machine
Our 8 modifications:
- 60° Nail Angle: We made the nail 60 degrees because another group calculated to get maximum distance the ideally nail angle should be 60 degrees. This makes the nail release at 30 degrees making the ball cut through the air more efficient and gain more distance.
- Spacers to reduce wobble: Adding spacers on either side of the arm increases distance by making more of the spring potential energy transfer into the ball's kinetic energy. We found that when the arm on had 0.5 cm of wobble the ball went 2m farther than the arm with 3.5 cm of wobble.
- Rubber bands over weights: Since rubber bands can accelerate faster than weights, rubber bands makes the ball go farther. The limitation to weights is gravity. A weight can only accelerate at 9.8 meters per second squared, but rubber bands can accelerate the arm faster.
- No arm stopper: Having a no arm stopper maximizes the distance of the ball. When there is no arm stopper the ball arm is able to rotate fully letting the ball realize when it has the most energy. This makes the ball go faster.
- Having a 15 cm string: The longer the string that is attached to the ball, the faster the ball goes. The time it takes for the ball to launch is going to stay the same but with a longer string the ball has to cover more distance making the ball go faster. But when the string gets too long, the ball gets caught on the ground so the ideal length of the string is 15 cm.
- 17g projectile: The ideal weight found by another group was 22.5 grams, but after using the 22.5 gram projectile it did not seem like it was going as far so we decided to switch to the 17 gram projectile. The group that did the research on the weight of the projectile found that the 22.5 gram ball went 2.75 meters and the 17 gram projectile went 2 meters but for our machine the 17 gram projectile went farther.
- Tape around the ball: Our machine has too much force. Other groups might have wanted more force but when the ball would be fired the string would rip out of the clay. To fix this we put tape around the ball to prevent the string from leaving the ball. Even though this would work for about 10 fires the string would eventually rip through the tape.
- Size 64 rubber bands: Another group concluded that 1 size 64 band went 8 meters farther than a long and skinny rubber band. After hearing about this modification, we decided not to switch to long and skinny rubber bands. With size 64 rubber bands we achieve the farthest distance.
How to maximum distance with a trebuchet
When using a trebuchet, the less space between the arm and the legs(less wobble), the further the projectile will go. In this project, we were assigned to build a trebuchet that launches a clay ball as far as possible. The trebuchet works by applying a force downwards on one side of a lever that then launches a ball upwards on the other side. We tested if having wobble on the lever would affect how far the ball goes. We found that the arm with 0.5 cm of wobble went and average of 14 meters. The ball with 3.5 cm of wobble went an average of 11.8. This means that the ball went about 2 meters farther with the less wobble. That means if you are building a trebuchet make sure to have as little of wobble as possible on the lever to maximum distance.
Technical Specifications
- Mass of projectile: 0.0175 KG This is the weight of the clay ball that was fired.
- Horizontal Distance: 38 meters. This is how far the clay ball was fired.
- Time in Air: 1.725 seconds. This is the time the clay ball was in the air.
- Vertical Distance: 14.58 meters. This is how high the ball went.
- Horizontal Velocity: 22.03 meters per second. This is how fast the ball went horizontally.
- Vertical Velocity: 16.9 meters per second. This how fast the ball went vertically.
- Total Velocity: 27.77 meters per second. This how fast the ball moves through the air.
- Angle of release: 60 degrees. This is the angle when the ball leaves the machine.
- Spring Constant: 420 newton meters. This is how much force the rubber band can hold.
- Spring Potential Energy: 22.869 Joules. This is how much energy is stored in the rubber bands when in the fully loaded position.
- Kinetic energy of the ball: 6.55 Joules. This is how much energy the ball has when moving through the air.
- Energy converted: 29%. How much potential energy is converted to kinetic energy.
Why buy this machine
- Light weight
- Very efficient
- Launches up to 38 meters
- Uses state of the art rubber bands
- Uses patent pending spacers to reduce wobble.
5 Meter Zip Line "Hybrid Car"
What did we do:
In this project were assigned to make a machine to move two roll of pennies "passengers" 5 meters. We started by brainstorming some ideas. We settled on making a zip line that held the passengers while a solar powered car towed them. After building the level zip line and the solar car we realized the solar motor did not have enough torque to even push the car. After this setback we decided to scrap the solar car idea and make a zip line.
To make our current zip line work we needed to raise on of the towers to give the pennies more potential energy. Next we focused on getting the pennies to the top of the zip line. We achieved this by making an elevator that used two 200g weights pulling down on one side of a pulley to pull the elevator capsule up. Once the elevator was mastered we made a lightweight and aerodynamic cart out of legos. With these three elements mastered we had a premium zip line that lived up to its quality.
To make our current zip line work we needed to raise on of the towers to give the pennies more potential energy. Next we focused on getting the pennies to the top of the zip line. We achieved this by making an elevator that used two 200g weights pulling down on one side of a pulley to pull the elevator capsule up. Once the elevator was mastered we made a lightweight and aerodynamic cart out of legos. With these three elements mastered we had a premium zip line that lived up to its quality.
Content:
Distance vs time: This is how much time it took for our machine to cover each individual meter.
Velocity: This is represented in meters per second. This is how many meters and object can cover in one second.
Gravitational Potential Energy: This is how much energy and object has due to its position at a height or in a gravitational field.
Kinetic Energy: This is how much energy an object has when it is in motion.
Thermal Energy: This is how much energy is converted to heat from other energy object.
Thermal Energy and the conservation of energy. Energy can not be created or destroyed but it can change forms. All energy in all forms will eventually convert to thermal energy which is heat.
Friction: This is one of the processes to make thermal energy which involves to objects touching each other.
Velocity: This is represented in meters per second. This is how many meters and object can cover in one second.
Gravitational Potential Energy: This is how much energy and object has due to its position at a height or in a gravitational field.
Kinetic Energy: This is how much energy an object has when it is in motion.
Thermal Energy: This is how much energy is converted to heat from other energy object.
Thermal Energy and the conservation of energy. Energy can not be created or destroyed but it can change forms. All energy in all forms will eventually convert to thermal energy which is heat.
Friction: This is one of the processes to make thermal energy which involves to objects touching each other.
Reflection:
This was a very fun project we had lots of time to work with the group to build awesome machines. The first thing I did well on the project was helping the team in engineering the machines. I felt sometimes other group members were lost on what to do and I thing I helped them be finding solution to fix problems with the machines. Other thing I did well was letting other group members build the machines. I often like leading the group in building things and this project I stepped back to let other group members take the lead.
What I could improve on next project is making sure other group members not be distracted by outside sources. For example when another group member comes to distract one of my group members to ask polity for them to stop distracting us. Other thing I need to work on is letting other group members design the projects. For this last project I was the one who took a lot of resonsbility in engineering the machine and did not ask for other group member input. But overall I really enjoyed working with this group on this project and would love to work with them again on another project.
What I could improve on next project is making sure other group members not be distracted by outside sources. For example when another group member comes to distract one of my group members to ask polity for them to stop distracting us. Other thing I need to work on is letting other group members design the projects. For this last project I was the one who took a lot of resonsbility in engineering the machine and did not ask for other group member input. But overall I really enjoyed working with this group on this project and would love to work with them again on another project.