Our goal when making our trebuchet was to, launch our projectile as far as possible. With this, we had to meet certain requirements our projecting arm could not be more than one meter in any dimension and we were advised to have a ball with a mass of around 10grams. After the initial assembly of our machine, we looked at areas we could improve in and made necessary changes. Our design has a large wooden base with two parallel pieces of wood in a vertical position. We complete that with a metal rod, attached to a set of rubber bands, to create the needed force for our projectile. Our design
wood base (57x13.5x4cm)
arm (79.5x4x2cm) with two parallel holes
rubber bands (6)
axle from base (30.5cm)
angle of nail (60 degrees)
screw (3)
legs (33cm)
projectile, clay ball (10g)
Modifications
no arm stopper
A stopper has no effect on the release of our ball, the Projectile releases before it meets the stopper
10g ball
This mass was shown to travel the farthest distance for our given proportions. With our given force and inertia, we found That the 10g ball would travel the most distance with the least Amount of Effort.
65 degree forward nail for projectile
Our nail had a medium to small size head, my group found that When our nail was faced forward at a 60 degree angle, our projectile traveled the farthest distance while going in our desired direction.
thicker and longer rubber bands
Thicker and longer rubber bands helped give us our our desired force, to launch our projectile.
30cm string We found that using a 30cm string gave us our desired distance
and leverage.
6 rubber bands Using 6 rubber bands gave us our desired force, we found that
using more or less than 6 bands negatively affected our machine.
Remove notch for full rotation
After many trials, it was discovered that having a stopper only essened our follow through force, ultimately making our machine travel less distance
holes in projecting arm to minimize weight
We found that, Having a minimal weight arm helped our projectile travel a much shorter distance. Our goal was to have the weight of our arm effect our projectile motion as little as possible. How to maximize the distance of a trebuchet we accomplished the max distance of our trebuchet, by completing these simple steps. We found that the less distance between the arm and the leg(less wobble), the further our projectile would travel. Our trebuchet works by applying force downward in order to launch our projectile forward. We wanted to test whether having wobble would positively or negatively affect the distance of our projectile. We tested this with a series of trials. We found that the arm with a 0.5 cm gap of wobble went an average of 14 meters. The trial with a 3.5 cm of wobble went an average of 11.8 meters. that indicates that you should have a slight wobble when building a max distance trebuchet.
Technical specifications of our machine
Mass of projectile (0.017kg) the weight of our projectile (clay ball
Horizontal distance (38m) how far our projectile traveled
Time in air (1.725s) time projectile was in the air.
Vertical distance (14.58) how high our projectile went.
Horizontal velocity (22.03m/s) how fast projectile traveled horizontally
Vertical velocity (16.9m/s) how far projectile went vertically
Total velocity (27.77) how fast projectile moves through the air.
Angle of release (60 degrees) angle at which the projectile leaves our machine.
Spring constant (420n/m) how much force rubber bands can hold.
Initial spring potential energy (22.869J) how much energy is stored in the rubber bands when in fully loaded position.
Kinetic energy of the ball (6.55J) how much energy the ball has when moving through the air.
Percent energy converted (29%) how much potential energy is converted to kinetic energy
Why buy our machine
Launches up to 38m
Very efficient
Light weight
Aesthetically pleasing
Has a high quality structure
5 meter zip line (hybrid car)
Our project
The goal of this project was to create a prototype of a hybrid vehicle to be as energy efficient as possible. We were required to have our machine travel a distance of 5 meters and carry a load of 250 grams. At the five meter line, our machine was required to come to a complete stop. With that, we had to apply some of our knowledge and create a sales pitch. My group decided to do this using a slides presentation.
Concepts
Velocity - the speed of an object in a direction Velocity - change in distance/change in time (m/s) Velocity - our machine had an average velocity of 4.92 meters per second as it traveled on a downwards slope.
Kinetic Energy - energy that a body possess by virtue of being in motion Kinetic Energy - ½ mass x velocity^2 (J) Kinetic Energy - our zip line had a max kinetic energy of 1.92 jules
Total Energy - all the energy within structure being observed Total Energy - thermal energy + potential energy + kinetic energy (J) Total Energy - our zipline had a total energy of 3.27 jules
Thermal Energy - energy that comes from heat. Energy lost to friction. Thermal Energy - Thermal energy -Kinetic energy -Potential energy (J)
Gravitational Potential Energy - an object's energy in relation to the ground Gravitational potential Energy - mass x acceleration due to gravity x height (J) Gravitational potential Energy - we had 3.27 jules of potential energy at the top of our Zipline.
Friction - A force opposing the direction of motion due to roughness at the molecular Level. we found that friction causes loss of potential energy
Reflection Over the course of the project, I feel that I did an impeccable job of staying positive and trying to solve minor problems that I otherwise would have freaked out about. My team and I worked very harmoniously together which made it easy to accomplish the task at hand. Our biggest struggle was time management, due to constant roadblocks when it came to things going the way we wanted them to in our design. By the end of our process, we were struggling quite a bit to finish in a timely manner. I feel I could have helped my team out, by taking a bigger role in our calculations process. We worked through many failed ideas, such as when we had the idea to make our machine solar powered. we brought in solar panels that ended up not having enough power to push our machine. After this roadblock, we ended up completely reworking our idea and structure. until we accomplished our goal. I feel my team and I did a good job of staying on task and working through our many ideas. Personally I believe I could have taken more leadership and been more assertive with ideas and solutions, but overall this project was a very fun and educational experience.