Fire Away!

Project Objectives: In this project we had to create a trebuchet. It could not be larger than 1 meter in all dimensions. We had to make it launch a ball of clay as far as possible.

Our trebuchet is made of all wood and a metal axel and a metal stopper, it has 7 rubber bands held by a screw in the board and a screw in the arm.


  1. Different cup size- we originally used a wheel but we found that a cup worked much better because the sides were taller.

  2. Different cup type- The design of the wheel was not fit for slinging a ball.

  3. More rubber bands- We were not getting enough force from the 5 rubber bands so we used 7 instead.

  4. Add lubricant- Helps to reduce friction of the arm on the axle.

  5. No stopper- having no stopper made our project worse because it eliminated energy transfer.

  6. Arm Length- The arm had originally been just around a meter, then when we cut it to 31-32 inches it was better. When our arm broke we made a new one that was shorter and worked even better.

  7. Axle height- We tried adding a lower axle but it didn't work as well because the amount of stretch on the rubber bands was more limited.

  8. Axle position- We tried it switch the position horizontally on the axle and the trebuchet didn't work as well so we changed it back.


5.

  • 11.6 gram projectile (ball) About the size of a large marble.

  • 16 meters (Where projectile landed)

  • 2.3 seconds (In air)

Calculations

Dv=(½ agtfall^2)=6.48m(21.26ft)

Vh=(Dh/t)=6.96m/s(16mph)

Vv=(agtfall)=11.28m/s(

Vtotal=(A^2+B^2=C^2)=13.1m/s

Release Angle=(tan X=vert/horiz)=58 degree

Spring Constant=(F/D)=122.5N/M per rubberband or total K(six rubber bands)=735N/M

Spring Potential Energy=(1/2kx^2)=4.4J Energy held by 6 fully stretched rubber bands

Kinetic Energy Of Ball=(1/2mV^2)=995.34J


Process: For this project we were assigned groups to work in. My group had 3 students in it. We were instructed about what to do by Mr. Williams. My group met and discussed how we wanted to do the project. We wanted to make our project out of just wood and a metal pipe. We built it in the makers space. When we originally built our trebuchet we used a wooden arm that ended up being too heavy. The arm broke. We had to re-think our design. We used a smaller wooden arm that worked much better. After changing to a lighter arm it launched the ball of clay much further.

Reflection: I felt that I did well working collaboratively in my group. My group split up the workload well and we were all productive in the makers space. This felt good because in one of my last projects the group didn't work evenly. I really noticed the difference with a group that put in equal effort. I also felt that I did a good job problem solving. I worked well with my group in identifying problems and solving them. Two things that I plan to work on with future projects are critical thinking and creativity. At times the calculations have been a bit challenging for me. Next time I want to put in more time studying the formulas. With creativity we went with a very basic or standard project. I'd like to step it up next time and do more designing to encourage myself to be more creative.