Trebuchet

Trebuchet design is based on distance. It is screwed into the top of a flat piece of wood for the base and then 2 heavy blocks at the bottom so when it fires most of the energy goes into the arm and not into the base or anything else. There are arms on each side that stick up 90 degrees and a metal rod to keep the swinging arm in place when it fires.

Selling Point.

The main selling point of our design is for fun and to learn the physics of a trebuchet. We have learned how to solve very complicated problems and now they are not so hard and don't look very complicated. The trebuchet is about power and stability because when you have power you need to have great stability to be on track.

Modifications

The Rubber Band Hook- When added a hook that succeeds the rubber band down better than other designs, the old design was a screw. When you shot the projectile the rubber bands would fly off but now with the new hook the rubber band would stay off and not fall off so there is a faster reload time.

The Arm Hole Placement- We had a Hole in the middle of the swing arm and it was getting the projectile far, we moved the arm in more and made another hole on the smaller side and now it goes much further than the old design.

Wider Base- We had a small skinny base in the beginning that was not working so well because we would have to stand on the side so it would not move or tip over. We added blocks on the bottom and widened the base to make it more stable and heavy, that made it so it would have more energy when the ball would be launched.

Rubber Bands- Are Projectile was not going as far as we would like it to, so why not put more rubber bands on. That's what we did, it launched further and was harder to pull back which was good for distance.

Nail Placement- We had nails in weird spots that almost poked out and was kind of a safety hazard so we moved them and the project is safe and not poke and dangerous

CER

Claim: More weight on the base increases the distance because more of the energy is transferred into the arm, therefore the ball should fly further and hit the ground at a further distance.

The Picture

Reasoning: Therefore, Adding a heavy base to the trebuchet has better results because it releases most of the energy into the arm and not into wiggling around and into the ground so you will get a greater distance. The graph shows a lighter weight is less distance and a heavy one is greater distance.

Technical Specifications

a. Mass of your projectile=15g

b. Horizontal Distance=25m

c. Time in air=1.55s

d. Vertical Distance (d = 1/2 a t^2) where t is the time falling.=11.76m

e. Horizontal velocity (v = d/t)=16.13m/s

f. Vertical velocity (v=at)=15.19m/s

g. Total velocity (a^2 + b^2 = c^2)=17m/s

h. Release angle (use protractor or tan x = vvert/vhoriz)=25degrees

i. Spring constant (k=F/d)=501N.m

j. Initial Spring Potential Energy (PEspring = 1/2 k x^2)=38.1J

k. Kinetic energy of the ball (KE = 1/2 m v^2)=0.688J

l. Percent energy converted (KE/PE)=0.018%