Amy'sTrebuchetProject

 =My Trebuchet Project~* =

__Purpose__

__Origin__

__Physics Principle__

__Materials__

__Procedures__

Diagram

Testing the Trebuchet

Results

Analysis


 * __Purpose: __**

To provide the Physics 30 students with hands-on application of the principles of physics and opportunity for creativity. Origin: __**
 * __

The trebuchet was invented in the medieval times to attack enemies by hurling rocks at the castle walls. It was a siege engine. Many believed that it was originated from China and was a further development of the Chinese traction trebuchet. Physics Principle: __**
 * __

A general trebuchet consists of a long beam which pivots around an axle with a sling attached to one end. It uses counterweight to propel the other end of the beam upwards to rotate the sling forward to release the projectile. When the trebuchet is in ready position, the weight possesses potential energy as it is pulled down by gravitational force. Once the arm is being let go, the counterweight, due to gravity, brings down one side of the lever, sending the throwing arm into air, transferring most of the energy towards the end of throwing arm. This gives the projectile its velocity when it is being released from the trebuchet. The principles of the trebuchet can also be explained by the 2nd and 3rd Newton’s laws of motion. The 2nd law states that an unbalanced force causes acceleration. (F=ma) When the string is released, the only force acting on the counterweight is the gravitational force. Therefore, it accelerates downwards. This action causes the reaction of the other end to propel upwards and release the projectile. This is Newton’s 3rd law of motion.


 * __Materials: __**

-Wood pieces -2’’ X 8’ (1) -2’’ X 2’ (2) -1’’ X 1’1’’ (2) -2’’ X 1’1’’ (1) -3’’ X 5’’ (2) -1’’ X 3’3’’ (1) -Metal rod -11’’ <span style="color: #000000; font-family: 'Calibri','sans-serif'; font-size: 12pt; line-height: 115%; mso-ansi-language: EN-CA; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 11.0pt; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: PMingLiU; mso-fareast-language: ZH-TW; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; msoansilanguage: EN-CA; msoasciithemefont: minor-latin; msobidifontfamily: 'Times New Roman'; msobidifontsize: 11.0pt; msobidilanguage: AR-SA; msobidithemefont: minor-bidi; msofareastfontfamily: PMingLiU; msofareastlanguage: ZH-TW; msofareastthemefont: minor-fareast; msohansithemefont: minor-latin;">- Copper hinge X 1 - Metal Wire - String -Styrofoam cup - Plastic bottle X 1 - Sand - Plastic tubes X 2 - Nails - Mitre saw - Nailer + Air Compressor - 25’ measuring tape - Hand Saw - Pliers - Screwdriver - Scissors -Masking Tape - Double-sided tape - Drill


 * __Procedures: __**

Before I started building the trebuchet, I researched on the structure and building steps of the trebuchet. Then I went to buy materials at Home Depot. The following is a series of steps I took to build the trebuchet.

 1)  Cut the 2’’ X 8’ into 2 pieces and use that as the base.  2)    Attach those pieces together by nailing the 2’’ x 1’1’’ wood piece in the middle.  3)  <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Drill two matching holes in the two pieces of 2’’ x 2’ that can fit the metal rod.  <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 4)   <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">For the vertical support, join the 2’’ x 2’ together by nailing the two 3’’ x 5’’pieces together in the middle. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 5)  <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Now nail the vertical support and the base parts together to form a T-shaped structure. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 6)   <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">For the arm, attach the copper hinge on the 1’’ x 3’3’’ wooden stick at the pivot point. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 7)  <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Now put the metal rod through the drilled holes on the vertical support. Also include the plastic tubes and the arm in between the supports. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 8)   <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Fill the whole plastic bottle with sand and attach it onto the shorter end of the stick with some metal wires. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 9)  <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Cut the Styrofoam cup to the shape that can fit the Christmas ball and use double-sided tape to attach it to the longer end of the stick. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 10)   <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Measure and cut out enough string so that one end can pull the longer arm downwards and the other end is tied to a fixed point on the vertical support. This can allow the trebuchet to be in a ready position without holding on to it. <span style="font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"> 11)  <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Finally, cut extra wood off the ends of the base to reduce the weight and nail the two 1’’ x 1’1’’ pieces to each ends of the base to strengthen the trebuchet structure. <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;"><span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-font-size: 11.0pt; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; msobidifontfamily: Calibri; msobidifontsize: 11.0pt; msobidithemefont: minor-latin; msofareastfontfamily: Calibri; msofareastthemefont: minor-latin; msolist: Ignore;">

__ **Diagram:** __ **__ Testing the Trebuchet: __**

<span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">First, I tested the finished project with different heights the counterweight was released. I found out that 45 cm between the bottle and the ground was the best height to release the string. Secondly, I tested the trebuchet with different counterweights. I compared between the 1kg bottle of sand and the 2kg box of sand; and found out that the 2kg weight only made the projectile go 30cm-50cm further. Therefore, I chose to use the 1kg weight instead due to the usage of ratios for our performance marks. Thirdly, I tested the trebuchet with different lengths of the arm. I added another 1ft. to the original length and found out that it went about 60cm further. Therefore, I chose to use the original length to maximize my performance mark. Next, I experimented with the position of the pivot point. When I moved the pivot point upwards, away from the counterweight, the projectile seems to be shot at a lower angle and so it did not go as far. When I moved the pivot point downwards, toward the counterweight, the projectile was shot to a further spot. Therefore, I chose to put the pivot point there instead. When I have maximized the range of the projectile, I focused on how to reduce the mass of the trebuchet and the length of the arm. I cut extra wood off of the ends of the base, but that did not help as much as I thought. I tried to reduce the length of the arm. However, my performance marks went down instead. Therefore, I figured that my trebuchet is probably at its maximum strength. I did not add the sling on because when I tried to do so, the projectile ended up leaving the pouch before it was thrown horizontally. The sling would also add on to the length of the arm, so therefore, I did not leave the sling on.


 * __Results:__**


 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">Trial # || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">Mass (kg) || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">Arm Length (m) || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">Distance (m) || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">P=d/ml ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.5 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.17 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.6 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.20 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.8 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.27 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">4 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.1 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.7 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.03 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">5 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.1 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.4 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.94 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.1 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.6 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.00 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">7 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.1 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.9 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.09 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">8 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.1 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">6.8 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.06 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">9 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">3.0 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.15 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">5.74 || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">1.66 ||
 * <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">Average: || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;"> || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;"> || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;"> || <span style="display: block; font-family: Calibri; font-size: 12pt; msobidifontsize: 11.0pt; text-align: center;">2.05 ||

<span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">From the results above, we can see that the projectile was launched to a fair distance. However, the weight of the trebuchet and the arm length lowered my performance mark. I could have made my trebuchet a bit smaller and lighter, and attempt to maximize the range, so that I can get a higher performance mark. I could have used materials which weigh less and use a plastic rod instead of the metal one. I could have built my trebuchet in a smaller scale and have a shorter arm. I think it is ideal to have a value smaller than 1 for the arm length and the weight. So even if the projectile is thrown 4 metres, I would still have a performance mark larger than 4. Therefore, if I were to build another trebuchet, I would make one smaller in scale and try to maximize the range of the projectile. This way, the performance mark will be a lot bigger.
 * __<span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">Analysis: __**

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[] <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;"> [] <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt; msospacerun: yes;"> [] <span style="font-family: Calibri; font-size: 12pt; line-height: 115%; mso-bidi-font-size: 11.0pt; msobidifontsize: 11.0pt;">