Murlin Trebuchet Case Studies

Murlin Trebuchet


http://www.instructables.com/id/The-Marshmallow-Trebuchet/step1/A-Little-History-Design-Selection/

Summary

The way the Murlin Trebuchet works is by hanging a mass connected to a piece of rope that is wrapped around several arms to increase the tension in the rope.  Once the mass drops the rope well speed up and get faster due to acceleration, launch the object out of the sling.  I would like to work on this Trebuchet because it seems like the most efficient way of getting a far distance out of a Trebuchet.  Even though it seems complex in the building process, I looking forward too the challenge in building the Murlin Trebuchet.

 

Case Study #1

Rating (7/10)

 

Positives

• Gives a good description of the Murlin trebuchet and the task/ building process one has to go through to build a successful trebuchet.
• Also it explains why the Murlin is the most efficient trebuchet out of the three others.
• Has helpful videos and pictures exampling how the trebuchet works.

Negatives 

• Doesn't give information on the dimensions used to build the trebuchet.
• Key information is blocked by the school security system.

http://thehurl.wikidot.com/trebuchettypes:merlin

Case Study #2

Rating (7/10)

 

Positives

• Involves a video to show how Trebuchet works.
• Explains difficulties in the building process.
• Explains the positives and the building process.

Negative

• Doesn't state dimensions of Trebuchet.
• Not as much information as in Case study #1.

 

 

 

 

 

 

 

 



Sumobot Racer

                                                                                                     
 

Sumobot Racer

             

                   The project requirements were to build a Sumobot using the materials provided to complete a full lap in the hallway.   Now most groups were not able to reach the goal/ requirements to complete this project.  But we were one of the groups that did achieve the requirements all thanks to our smart design.  We took two lego wheels to use as our back wheels instead of the wheels provided because the lego wheels had more grip on the ground.  We also took the board of wood  provided and cut about 1/4 or a little less off to reduce the weight of the bot.  We then measured the distance of the two back tires and took that measurement and measured from the back of the bot to the front to place our front tire down.  We did this so we would have even weight distribution.

                 For the time trials our group finished first with a time of 2:24, we couldve gotten 2:04 but we had to take one time penlty because our car drove into a wall.  The second place team and the only other team with a time was the Hillbillys with a time of 2:50 they couldve beten our time but they took three time penlties because their car kept spinning out.

                 We would redesign our car by adding sides to the car or some sort of wings to prevent the car from crashing into the wall so we wouldnt have to take a time penlty.  We would also use a different method for putting the wheels on because they weren't straight on and the kept falling off a couple times.

Compound Machine

 Build a Compound Machine

 

 

        After testing the simple machines we were handed a new task which was to make a compound machine out of the pulley, wheel and axle, and the lever (we were not allowed to use the inclined plane) without an ideal mechanical advantage.  You most be thinking if there is no ideal mechanical advantage what was the point in combining the machines? Well to answer that question we had to try and get as high of a mechanical advantage as we could get.  And whatever mechanical advantage we got would be our grade which was written on the board what you have to get to get a certain grade.

 

       When we were working on this project we weren't really worried about what the other groups were making/ building, because we were focused on getting at least an A- on the machine.  Even though we weren't worried about the other groups it was still cool to see what some of them came up with especially Christian Merkle.  A problem we had with this project was finding a secure place to put our Lever, when attached to the pulley, and crank.  So to solve this problem we drilled 2 holes through the pieces of wood holding the pulley up right and pulled a piece of string through it connecting the Wheel & Axle, and Lever together while still incorporating the pulley in the middle.  At first our method didn't really work but we made some adjustments, and at the end it all came together getting us a mechanical advantage of 39 which gave us a B+, not what we wanted to get but it was acceptable.  We could have focused more on our project instead of talking to the other groups and getting distracted.

 

      The most difficult part about this assignment was putting the three machines together, and having them all work together to move the nails, and the get an accurate read on the spring scale.  The mechanical advantage my group got was extremely surprising because it took a while to get the three together.  I could apply the knowledge that I learned from this project to a future experiment that involves putting together 2 other machines or invention, because now I know what I did wrong and what I have to fix in the future.             

 

Simple Machines

Simple Machines



 

                        Wheel & Axle
                      Zach & Finbarr

                          Lever
                     Ian & Finbarr 

 

 Inclinede Plane Ian & Zach
                

                           Pulley

                  Zach, Ian & Finbarr

 

               We made simple machines to test for a specific mechanical advantage assigned by Mr.Atkins.  The ideal mechanical advantage for the Wheel and Axle, Inclined plane, and Lever was 6; and the ideal mechanical advantage for the pulley was 2.  The way we test for the mechanical advantage was using a box of nails as a weight for the Lever, inclined plane and pulley, then using the spring scale to get the measurement of the input force for all the machine. 

 

               When we tested the machines against the other groups we tied for 3rd in the Wheel &Axle with 69.99% efficiency, then we tied for 3rd again in the Inclined Plane with 36.5% efficiency, next we tied for first in the Lever having a mechanical advantage of 73% efficiency, finally our pulley got 4th with 73% efficiency.  It was hard to pick a winner because of all the disqualifications of the other groups machines, but if it was up to me, I believe my group won considering we were not disqualified and we placed top 3, 3 times out of the four machines.

 

               For the results my group did not get 100% efficiency in any of our machines because we were a little off on the measurements of our machines which changed the mechanical advantage drastically.  When our machines tested they function well but not well enough to hit 100% efficiency.  We could have changed the measurements of the wood we used mainly for the wheel & axle because the circle we cut out originally was way to big, so we had to cut out a last second circle which wasn't the  exact measurement we needed to get 100% efficiency in the wheel & axle.