Physics Trebuchet

Introduction: Physics Trebuchet

We made our base using wood. We measured out the wooden platform to be 18 inches by 24 inches. We then used wooden planks to act as the base for the platform to be placed on. The planks were 22 inches and 28 inches in length. The extra wood at the end of the 28 inch planks were used for carrying purposes. One thin wooden plank that was again 28 inches was nailed and drilled into the base for it to stick up in the middle. a smaller but more dense wooden plank was nailed into this thinner wooden plank to create stronger up-right supports. This smaller piece of wood was about 2 inches bigger than the thinner wooden plank to allow space for holes that will fit the wooden dowel to create the axis. Metal reinforcements were attached to the corners of the base to provide more stability. Reinforcements were also attached to the throwing arm where the dowel went through to also provide more stability.

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Step 1: The Trial and Error Proccess

To provide even more stability, the angled wooden support braces were added to each side of the up-right supports. These were measured to start at about 3/4 of the up-right support braces. Another thin wooden plank was created to act as the throwing arm. We then measured two more wooden planks that were about 1/4 of the length of the throwing arm to give more weight to the side of the arm that was to be the counterweight. These wooden planks were attached by wood glue to either side of the arm. Two smaller wooden planks were measured out to add to either side of the arm again to provide more weight. A much smaller and thinner wooden plank was then nailed about halfway of the throwing arm. This was meant to provide more distance for the throwing arm so that when the projectile was thrown it would throw farther. The plastic bucket was nailed to this wooden plank to act as the pouch in which the projectile would lie in before being thrown out. We found that this type of pouch for the projectile did not give the fulcrum motion the throwing arm of the trebuchet would need to shoot farther. We even cut this plastic bucket to be more angled, similar to that of a lacrosse stick head, but we achieved the same results.

Step 2: Adjusting the Arm

We found that the small wooden plank needed to be removed as we were going to use the larger wooden plank with the dowel through it to be the final throwing arm. We drilled another hole so that more length was given to the upper side of the dowel to create a longer arm to maximize the distance of the projectile. We then drilled two key holes onto the side of the throwing arm that was parallel to the ground, one was closer to the end of the plank and the other was measured a few inches away. We then added key holes to the several wooden planks that was to be the counterweight. These key holes would allow us to string a bucket through to create a heavier counterweight. Adding the bucket also lets us adjust the counterweight as needed. For the trigger. We drilled a key hole into the base and connected a chain to it. This chain was then connected to a carefully bent metal wire hanger that was to go through the key hole closest to the end of the throwing arm. A chain was attached to the other side of the hanger and string attached to this chain to trigger the release. String was strung through the second key hole we made on the throwing arm. A nail was hammered through the top of the arm at an angle of 35 degrees. Another string was added to this nail. Then using a surgical mask as our pouch, we measured the strings to be even enough so that the pouch for the projectile was centered. The strings were measured to be about 20 inches and 22 inches with the longer string attached to the nail instead of the key hole. As we tried out the trebuchet, it did shoot farther but our trigger seemed to restrict the throwing arm. Instead we used a meter stick placed under the counterweight as our trigger. Our results improved greatly this way.

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    4 years ago

    Very cool!