AngelinaA+and+AmandaR+Trebuchet+Project

Introduction
Trebuchets were first used in China for the purpose of offensive and defensive strategies in warfare. Through time they made their way around the world and into the gym of Walter Murray. Their purpose here is not to destroy other things but rather to launch a Christmas ball. The horizontal distances of the various models will be measured and recorded, using the formula: d/ml, where the distance is measured in meters and divided by the mass in kilograms and the length of the arm. After many hours of trial and error, we are please to present the working model of our trebuchet and how it was created.

 Applicable Physics Principals
// Projectile motion //  – When the nail is bent at a certain angle at the end of arm it causes the sling to open up, releasing the Christmas ornament. Once the sling, hopefully, comes off at 45 degrees the ball will launch itself in a parabolic arc. If the sling does come off at 45 degrees, you are typically maximizing the trebuchets performance. //

Forces //  – Applied force to launch the Christmas ball, to straighten out the sling and for it to come out of the nail. Also, the air resistance, gravity etc. have a major effect on the performance of a trebuchet. // Newton ////’s laws //  – 1st Law: An object at rest stays at rest and an object in motion stays in motion until a force acts upon it. The Christmas ornament stays in a line with sling until the sling falls off meaning, the sling has stopped acting upon it. 2nd Law: F = ma. The force and acceleration are both going in the same direction. So increase the mass of the Christmas ornaments will then increase the force of the Christmas ornament. // Centripetal Force - // Keeps the sling intact and hung onto the nail until the moment the arm slows down from the counterweight. The sling then comes off of the nail which then releases the christmas ornament from the pouch.

 Procedure
1. All of the wood material was cut to their appropriate measurement first (see in materials.)

2. After all the wood is cut we used screws to attach the upright pieces to the base, making sure they were 90 degrees. Then attached the three base stands to the bottom of the base. Two at each end of the main base and the other base stand, 63 cm away from the front of the main base to keep the uprights in place.

3. Attached the diagonal braces to the uprights and the front base stand. After we attached the trigger plate to the end of base.

4. We assembled the counterweight pieces next. Starting with cutting a slot in both end pieces so that the arm wouldn’t get blocked. Then aligned the bottom of counterweight with the end pieces. The side plates were then screwed to the end pieces.

5. Then the hardest part to assemble was next, the sling. We tied a string around the four nails that we had on our string template (see in materials.) After, we cut a 20 cm piece of duct tape to the center, with the sticky side up first on the strings. Then another 20 cm piece of duct tape on top of the strings which would soon be our pouch.

6. We released the nails from our template and then cut two narrow strips of duct tape to shape the duct tape into a pouch.

7. For the arm, we used a loop of wire to attach one end of the sling to the hole at the end of the arm. Another wire was attached to the nail at the end of the arm with the other end of the sling.

8. In the end, we taped another loop of wire to the back of our pouch so that it would be easier to let go when we launched the trebuchet.  

<span style="font-family: Georgia,serif; font-size: 90%;">Materials
<span style="font-family: Georgia,serif; font-size: 13px;"> 1) Wood a. Weight box i. 15cm x 36cm (2) ii. 24cm x 16.5cm (2) iii. 15cm x 16.5cm

b. Throwing arm i. 9cm x 114cm

c. Main Base i. 27cm x 90cm ii. 11.4cm x 42cm (3) iii. 84cm x 5.4cm (2)

d. Trigger Block i. 5.4cm x 22.5cm

e. Sling template i. 165.3cm x 6cm

2) Nails 3) String 4) Drill 5) Electric Saw 6) Pencil 7) Ruler 8) Calculator 9) Wire 10) Duct Tape/ Scotch Tape 11) Hammer <span style="font-family: Georgia,serif; font-size: 13px; line-height: 22px;"> <span style="font-family: Georgia,serif; font-size: 15px; line-height: 22px;">

<span style="font-family: Georgia,serif; font-size: 90%;">Photo
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<span style="font-family: Georgia,serif; font-size: 90%;">Procedure We Used to Test Our Trebuchet
<span style="font-family: Georgia,serif;"> To test our trebuchet, we launched our Christmas ornament and watched at what angle the pouch was releasing it at. We would not adjust anything until we got the same result twice in a row, due to the fact that the first time might have been inacurate. We also launched the sling without the use of the Christmas ornament so we would see how fast the arm was swinging and at where the Christmas ornament would release.

<span style="font-family: Georgia,serif; font-size: 90%;"> Measurement and Calculations

 * <span style="font-family: Georgia,serif; font-size: 13px;">Trial # || <span style="font-family: Georgia,serif; font-size: 13px;">Mass (kg) || <span style="font-family: Georgia,serif; font-size: 13px;">Arm length (m) || <span style="font-family: Georgia,serif; font-size: 13px;">Distance (m) || <span style="font-family: Georgia,serif; font-size: 13px;">P d/ml ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">12 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">7.92 || <span style="font-family: Georgia,serif; font-size: 13px;">1 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">3 || <span style="font-family: Georgia,serif; font-size: 13px;">12 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">7.62 || <span style="font-family: Georgia,serif;">0. 8 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">4 || <span style="font-family: Georgia,serif; font-size: 13px;">12.5 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">8.84 || <span style="font-family: Georgia,serif; font-size: 13px;">1.4 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">5 || <span style="font-family: Georgia,serif; font-size: 13px;">12 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">7.92 || <span style="font-family: Georgia,serif; font-size: 13px;">1 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">6 || <span style="font-family: Georgia,serif; font-size: 13px;">12 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">9.45 || <span style="font-family: Georgia,serif; font-size: 13px;">1.5 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">7 || <span style="font-family: Georgia,serif; font-size: 13px;">12 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">7.92 || <span style="font-family: Georgia,serif; font-size: 13px;">1 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">8 || <span style="font-family: Georgia,serif; font-size: 13px;">12 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">8.23 || <span style="font-family: Georgia,serif; font-size: 13px;">1.2 ||
 * <span style="font-family: Georgia,serif; font-size: 13px;">9 || <span style="font-family: Georgia,serif; font-size: 13px;">12.5 || <span style="font-family: Georgia,serif;">2 || <span style="font-family: Georgia,serif; font-size: 13px;">8.53 || <span style="font-family: Georgia,serif; font-size: 13px;">1.3 ||

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<span style="font-family: Georgia,serif; font-size: 90%;">Changes Made to the Trebuchet to Maximize Performance
<span style="font-family: Georgia,serif;"> 1) Problem: The ball would not release from the pouch To solve this, we created a slot at the end of the arm. We also made a loop at one end of the string attached to the pouch. The loop would be placed in the slot and would come out when the arm swung forward, opening the pouch to release the ball.

2) Problem: The loop came out of the slot too soon, opening the pouch and firing the ball straight up, rather than at a 45° angle. To solve this we covered up the slot at the end of the trebuchet and replaced it with a nail. With a nail we were able to adjust the angle the loop was released by bending the nail.

3) Problem: Weight of trebuchet To solve this we made a series of holes along the length of our arm

4) Problem: The ball was still not releasing from the pouch consistently To solve this we made our pouch smaller

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<span style="font-family: Georgia,serif; font-weight: normal;">In the end, our trebuchet had a decent turnout. It was fun getting the trebuchet together but there were moments of cluelessness. If we were to make this project again we would cut much of the mass and maybe play with the sling and the different angles with the nail, if we stayed with the same model. But, if we were to do a different model we would do the floating arm trebuchet because it seems to be the most efficient with the results that came out during other peoples trial runs.

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