Hybrid Car/Trebuchet
Fire Away!
Proof of Efficacy Document
mass=22.5g; This means that the amount of matter in the piece of clay which was launched is 22.5 grams.
hd=9.75m; This means that horizontal distance traveled by the piece of clay during the launch is 9.75 meters
t=2.8s; This means that the amount of time which the launch took is 2.8 seconds
vd=((9.8m/s^2)/2)*2.8s^2=4.9m/s^2*7.84s^2=38.416; This means that the highest point which the clay ball travelled was 4.9 meters.
hv=9.75m/2.8s=3.48214286m/s; This means that the velocity at which the ball travelled horizontally during the launch is 3.48214286 meters per second.
vv=9.8m/s^2*2.8s=27.44m/s; This means that the velocity at which the ball travelled horizontally during the launch is 27.44 meters per second.
3.48214286m/s^2+27.44m/s^2=tv^2;(12.1253189+752.9536)=(765.078919)=27.66006m/s=tv; This means that the total velocity taken from the Pythagorean Theorem, is 27.66006 meters per second.
35° This means that the angle at which the clay projectile was shot was 35° relative to the ground.
k=(22.5g*9.8m/s)/9.75m=220.5N/9.75m=22.6153846; This means that the spring constant for the catapult is 22.6153846.
PE= ½(22.6153846)*9.75m/s=11.3076923*95.0625=1074.9375J; This means that the Potential energy, or the maximum energy that can be exerted from or on the clay projectile is 1074.9375 Joules.
KE= ½(22.5g)(9.75m/s^2)=11.25g(95.0625m/s)=1069.45312J; This means that the actual energy that was exerted on the clay projectile is 1069.45312 Joules.
1069.45312J/1074.9375J=0.99489795=99.489795%; This means that the efficiency of the catapult is 99.489795%
Our design consistently launches the projectile at least 9 meters along the relevant horizontal axis. It was designed using handpicked modifications and is very efficient. Its beauty lies in its simplicity, despite being modified in many ways. Moreover, this design includes a 22.5 gram clay projectile, which is ideal for long-distance launches.
- Our design has a projectile attached to an eight inch string on one side and 3 pairs of rubber bands attached to a nail that is at a 60 degree angle on the other. Both sides are even and there is a rubber band-stopper directly above the fulcrum. There are also a few rubber bands below the axis that are to be used as replacements should the current pairs break. These are all situated above a large wooden board and between two planks where the pivot lies.
- My group and I chose to angle the rubber band nail properly, attach a stopper, use rubber bands instead of weights, have 6 rubber bands, have a 22.5 gram projectile, have equally long sides, and an 8” string on the projectile. We chose to angle the rubber band nail properly because it yielded great results for the group that suggested it. It also happened to work just as well for our group once we decided to adopt the feature. We attached a stopper because it would consistently set the release angle at an ideal value. We decided to use rubber bands instead of weights because with weights, we were getting substandard results. We decided to use three pairs of rubber bands in order to optimize the momentum, and therefore distance of the projectile. We decided to have a 22.5 gram projectile because it worked for the group who had suggested it and it seemed too precise to fail. It did end up working for us, but if our design had been a little different, we would have had to retreat and further innovate. We decided to have equally long sides because it seemed favorable according to experimentation. We chose to have an 8 inch string on the projectile because the mass would have a later release which is ideal for the situation.While it might have been better to employ different modifications, I believe that the ones that we used greatly improved our catapult in terms of distance and momentum.
- The mass will travel further when the load and effort sides are equal. This is true because the lever would have a mechanical advantage of 1 and no energy would be wasted when lifting the effort arm. Also, the rubber bands are not overstretched and the mass will not be released prematurely or too late.Our evidence of this is that when the effort length was 32 centimeters and the load was 20 centimeters, it went an average of 3.3 meters and when the load was 30 centimeters and the effort was 22 centimeters, it went an average of 9 meters while when the load was 26 centimeters and the effort was at 24 centimeters, the average distance was 15 meters. This means that when we tested the different lengths, the launches that had effort/length ratios further from one were shorter than those closer to one. This is a clear trend in our data throughout the experiments.
mass=22.5g; This means that the amount of matter in the piece of clay which was launched is 22.5 grams.
hd=9.75m; This means that horizontal distance traveled by the piece of clay during the launch is 9.75 meters
t=2.8s; This means that the amount of time which the launch took is 2.8 seconds
vd=((9.8m/s^2)/2)*2.8s^2=4.9m/s^2*7.84s^2=38.416; This means that the highest point which the clay ball travelled was 4.9 meters.
hv=9.75m/2.8s=3.48214286m/s; This means that the velocity at which the ball travelled horizontally during the launch is 3.48214286 meters per second.
vv=9.8m/s^2*2.8s=27.44m/s; This means that the velocity at which the ball travelled horizontally during the launch is 27.44 meters per second.
3.48214286m/s^2+27.44m/s^2=tv^2;(12.1253189+752.9536)=(765.078919)=27.66006m/s=tv; This means that the total velocity taken from the Pythagorean Theorem, is 27.66006 meters per second.
35° This means that the angle at which the clay projectile was shot was 35° relative to the ground.
k=(22.5g*9.8m/s)/9.75m=220.5N/9.75m=22.6153846; This means that the spring constant for the catapult is 22.6153846.
PE= ½(22.6153846)*9.75m/s=11.3076923*95.0625=1074.9375J; This means that the Potential energy, or the maximum energy that can be exerted from or on the clay projectile is 1074.9375 Joules.
KE= ½(22.5g)(9.75m/s^2)=11.25g(95.0625m/s)=1069.45312J; This means that the actual energy that was exerted on the clay projectile is 1069.45312 Joules.
1069.45312J/1074.9375J=0.99489795=99.489795%; This means that the efficiency of the catapult is 99.489795%
Our design consistently launches the projectile at least 9 meters along the relevant horizontal axis. It was designed using handpicked modifications and is very efficient. Its beauty lies in its simplicity, despite being modified in many ways. Moreover, this design includes a 22.5 gram clay projectile, which is ideal for long-distance launches.
Hybrid Car
The hybrid car that I made with my group is solar powered and has four wheels. However, the string, which stops its motion, only goes to a single wheel, which means that once it has reached its destination, it will spin in place. It is constantly absorbing power from the sun and only works without shadows due to the lack of a battery in the vehicle. Because of its constant absorption of solar power, its thermal energy is constantly increasing alongside its total energy. Its kinetic and potential energy however, remained constant through most of the drive due to the capacity of the motor that is powered by the solar panel.
The process began when me and my fellow group members brainstormed general ideas for the vehicle design. After a couple strange ideas, such as a magnet slingshot or a a void, gravitational pendulum, we figured out that we should use solar panels to power the machine. We built it by wiring a solar panel to an engine, and building a frame out of popsicle sticks and Legos. We then added Lego wheels and the engine to the Lego base and attached a string to the middle part of the base where the wheels were attached. This made it so that, at the end of five meters the wheels would stop turning due to the friction of the string (which was the goal). It fits two rolls of pennies. Below is a photo of the car:
The process began when me and my fellow group members brainstormed general ideas for the vehicle design. After a couple strange ideas, such as a magnet slingshot or a a void, gravitational pendulum, we figured out that we should use solar panels to power the machine. We built it by wiring a solar panel to an engine, and building a frame out of popsicle sticks and Legos. We then added Lego wheels and the engine to the Lego base and attached a string to the middle part of the base where the wheels were attached. This made it so that, at the end of five meters the wheels would stop turning due to the friction of the string (which was the goal). It fits two rolls of pennies. Below is a photo of the car:
Reflection
By working on this project, I learned many things, both about science and about the world. First of all, I learned about spring constants and how spring power is more efficient than gravitational power. Second of all, I learned that solar power is more efficient than magnetic power, because true magnetic power is hard to maintain and electromagnetic power costs electricity. Then, I learned that your own idea is not always the best one because we, as human beings, constantly overlook details and make mistakes. Lastly, I learned that no matter who you are and whatever your background, when you are on a team, hard work always pays off.