Fire Away!

In this project we were required to create a catapult that can launch a projectile. Then, we were to create a "Proof of Efficacy Document", where we showed what our catapult was best at. Our catapult we created was named "Captain Hook", due to it's hook at the head of the arm. Our catapult is most effective at shooting up high.

Abhiram Satyavolu - Proof of Efficacy Document for Trebuchet

Content

Initial Spring Potential Energy

PEspring=12kx2

PEspring=12(245N/m)(.35m)2

PEspring=15J

Kinetic Energy of Ball

KE=12mv2

KE=12(0.01kg)(15.3m/s)2

KE=11.7J

Spring Constant+Gravitational Potential Energy

k=Fd

F=mag

F=(0.5kg)(9.8m/s2)

F=4.9N

k=4.9N 0.3m(15rubberbands)

k=245N/m

Thermal Energy

PE-KE=TE

15J-11.7J=TE

TE=3.3J

Vertical Distance

dv=12 at2

dv=12 (9.8m/s2)(1.25s)2

dv=7.66m

Horizontal Velocity

vh=dt

vh=22m2.5

vh=9.2m/s

Vertical Velocity

vv=atfall

vv=(9.8m/s2)(1.25s)

vv=12.25m/s

Total Velocity

vh2+vv2=vtotal2

(9.2m/s)2(12.25m/s)2=vtotal2

vtotal=15.2m/s

Release Angle

arctan(vv/vh)= theta

arctan(12.25m/s9.2m/s)= theta

arctan(1.33)=53

Percent Converted

%converted=KEPE

%converted=11.7J15J

%converted=78%

Reflection

This project was a blast to create and test. Just coming up with ridiculous ideas and trying to incorporate them into our project provided great fun to the building. Despite the short build time, I found this project to be very comprehensive in terms of learning, discoving concepts involing springs and their conversion of energy.

I personally thought I was involved in the testing process, as well as actively coming up with new ideas during brainstorming. I do wish we had a more serious tone when building however. Despite the amount of fun it was, it was quite hard to concentrate and get the project finished, which is where i suffered.

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