Angela+and+Rainie+Proj

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** __Trebuchet:__ **A medieval machine designed to launch projectiles at walls to break it down or go over them, with more precision than a catapult. We are building our own trebuchet to better understand the principles of physics applied. ======

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A projectile is an object which after an initial force that launches it, there is no force acting on it except for acceleration due to gravity and air resistance. This applies to the christmas ball, after it is launched by the force from the counterweight, the only force that slows it down is friction from air resistance and gravity. ======

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Newton's laws states that objects in motion stays in motion and objects at rest stays at rest, unless an external force is applied. The ball was at rest untill a force was applied and it stayed in motion untill air resistance and gravity stoped it. Newton also stated F=ma, an unbalanced force causes acceleration. The gravitational force acting on the counterweight which cause the acceleration going downwards. The acceleration of the ball is the result of the force applied divided by the mass. This is important to our trebuchet because the weight we use is inversely proportional to the acceleration of the ball, the net force is directly proportional to the acceleration. which will affect it's distance. The larger the mass of the abject, the smaller the acceleration. A massive body has more inertia than a less massive body.(more mass, more inertia) ======

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We have a lever type trebuchet. So as one side of the fulcrum goes down, the other side goes up. And because the fulcrum is closer to oneside with a heavier load, as it goes down it forces the other side to go up really fast which throws the ball. ======

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According to the //law of conservation energy//, energy can not be created or destroyed, only transformed and transfered. With our trebuchet, there was potential energy when we held down one end of the arm and when we let go, it uses the gravitational potential energy from the counterweight to move the ball. ======

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 * After we decided on the design, size, and had all the materials needed we began to build. We had help from the woodshop and electrical teachers because we lacked the tools necessary to cut the woods and drill the holes. **======
 * 1) We cut a big piece of wood into four even pieces (labelled 1, 2, 3, and 4) which will be the frame/support. Then we sawed the end of 2 and 4 off so that they can be slanted against 1 and 3.
 * 2) We drilled a hole in the 1 meter wood (arm) 30cm from the top as well as pieces 1 and 3 near the top, so that a pole could be put through.
 * 3) Next with wood piece 1 at 45 degrees we glued piece 2 to its side, creating an angle. Then a triangle was nailed to where the two pieces joined and screws are added from the side to keep then together. The same is done to pieces 3 and 4.
 * 4) Then we took the two supports and screwed them on either side of the baseboard, drilling a hole first so the wood would not crack.
 * 5) For the arm, we drilled a smaller hole near the end where the counterweight will go and inserted a machine screw secured with 3 bolts, leaving enough room to hang the weights.
 * 6) Using tinfoil, we make a little holder for the Christmas ball and using tape and sticky tack secured it to the other end on the arm.
 * 7) For the counterweight, we twisted 6-7 strands of thin wires together and looped it through a tin basket and hang it on the machine screw. By removing the original handle first, we can adjust the lenght of our counterweight.
 * 8) Then we assembled everything together. Put the pole through the holes and used sticky tack to fill in the gap of the two supports because the hole was too big and the pole moved with the arm. Added the basket to the screw in the arm and started the testing.

__**List of Materials:**__ 7 pieces of wood -arm (100cm x 1.7cm x 3.6cm) -base (21.5cm x 57.5cm) -frame(4) (4cm x 61cm x 1.8cm) -pole (40cm x 1cm diameter) nails screws bolt tin basket weights glue tinfoil sticky tack wires **__Tools Used:__** Measure tape/meter stick screwdriver wrench saw hammer power drill various wood cutting tools

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 * __ Photos __**

Procedure of testing / Analysis: **__ We put the ball on the holder and launched it by holding down the arm with the ball, and then letting go allowing the force of the fall to propel the ball. We tried different weights to maximize our distance, but at the same time increase our performance mark. We tried from 2.5Kg to 500g and decided on 1.1kg, because the more weight we have the further the ball goes but eventually the increase in distance is not worth all the weight we had to add, it was only decreasing our P. The first basket we used was wood and broke under the strain of the weights so we changed it to metal. We also experimented with different arm lengths, and decided to keep it at one meter which gave us the most distance for the minimum weight. From our research online we found that 45 degree is the optimum angle to launch a projectile, so we adjusted the length of the wires holding the basket to stop when the arm reached 45 degrees; but the height of our trebuchet and the length of the arm with the counterweight made it difficult to achieve this angle. And the result was worse than when we had let it stop on it's own, so we abondoned this idea seeing it was too late to change the height.

__Trials__: **

1 || 3.5 || 1.28 || 5 || 1.12 || 2 || 3.5 || 1.28 || 4.9 || 1.1 || 3 || 3.5 || 1.28 || 5.3 || 1.18 || 4 || 3.5 || 1.28 || 5.6 || 1.25 || 5 || 3.5 || 1.28 || 5.47 || 1.22 || 6 || 3.5 || 1.28 || 5.33 || 1.19 || 7 || 3.5 || 1.28 || 4.9 || 1.1 || 8 || 3.5 || 1.28 || 5.5 || 1.23 || Average || 3.5 || 1.28 || 5.25 || 1.2 ||
 * Trial || Mass (Kg) || Arm Length (m) || Dist. (m) || P = d/ml ||

**__After Thought__** The result of our trebuchet was disappointing. We had a fairly simple design and didn't use that to its full advantage. I think if we had built a smaller model and used a different ratio for the counterweight and arm's length we could have achieved a better result. But we learned a lot from this activity and given the chance again I'm sure we could do better.