TREBUCHETReport Grading

Trebuchet

• The report will included the following information: (1) a word processed document, size 12 font, doubled spaced, (2) a very brief history on the trebuchet, (3) Physics based principles on how and why the trebuchet operates, (4) description on how the team designed, collected, assembled, and tested their trebuchet, (5) show calculations on computing trebuchet force, (6) data table showing team test results, (7) information on how much money is used in the building of the trebuchet, (8) correct writing method and procedures used in the report, (9) bibliography and internet sources listed.

Trebuchet

• Typed report – 20pts• Brief history – 20pts• Physics based principles – 20pts• Physics calculation – 20pts• Design & assembly – 10pts• Blue prints / pictures – 10pts• Data Table (test) – 50pts• Cost of project – 10pts• Bill of Material – 10pts• Correct writing – 20pts• Bibliography – 10pts• Possible 200 points

Trebuchet• Formulas• Torque on the counterweight and

projectile T= L x F

• Potential Energy of the counter weight Ep = W x h or Ep = m x g x h

• Kinetic energy of the projectile Ek = ½ w/g x V2 or Ek = ½ m x V2

• Speed of the projectile V = D/t

• Acceleration of an object Vf – Vi / t

• Efficiency = Workout / Workin x 100%

Trebuchet

• Bill of Material looks like this• Trebuchet• 6 @ 2” x 4” x 8’0” $3.25 = 19.50• 2 @ 2” x 10” x 10’0” $ 9.00 = 18.00• 1 @ 1” dia. X 4’0” $2.00 = 2.00• 1 @ 4” x 4” x 8’0” $ 8.00 = 8.00• 1 @ ¾” dia. x 25’0” rope $6.00 = 6.00• 3 @ Screw eyes 5/8” x 2” .75 = 2.25• 1 @ Bolt ½ x 6” 1.25 = 1.25• 50 @ nails 3” 3.00 = 3.00• Total 60.00

• Cost per team member 60.00/4 = 15.00

Trebuchet Calculations• Counter weight / projectile mass• Conversion lb x .453 = kilograms• Distance feet to meters• Conversion ft x .3048 = meters• Gravity Metric = 9.8 m/sec2

• Gravity English = 32 ft/sec2

• Potential Energy – English Ep= w x h

• Potential Energy – Metric Ep= m x g x h

• Velocity = Distance / time

• Acceleration a = Vf – Vi / t

• Kinetic Energy – English Ek = ½ w/g x v2

• Kinetic Energy – Metric Ek = ½ m x v2

• Torque = F x L• Work = T x Ɵ

• Mechanical Efficiency = Workout / Workin x %

Trebuchet

• Graph – should look like this.

Test Data

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12

Throws

Dis

tan

ce

Series1

Trebuchet

throw Distance

ft.Distance

M Reason1 15 4.57 Lengthen sling2 17 5.18 Lengthen sling3 18 5.49 Lengthen sling4 25 7.62 Lengthen sling5 37 11.28 Bent nail6 40 12.19 Changed sling7 0 0.00 New nail / Hook8 48 14.63 More weight9 57 17.37 More weight

10 65 19.81 More weight

Data Table should look like

Trebuchet

P.O.T. - Trebuchet Project - 150 Pts.        

Team 5thDesign

- 50Construction - 50

Distance-50

Ext

Dist pts.

Total %

1Brooklyn, Sarah, Dillan, Brittany 50 50 32 0 50.00 150 1.00

2 Nic, Sol, Tommy, Ray 45 45 1610 26.67 127 0.84

3 Kip, Mark 50 50 5010 83.37 193 1.29

4Tyson, Josh, MaCauley, Tate 0 0 0 0 0.00 0 0.00

5 Amy, Sarah, Luke 0 0 0 0 0.00 0 0.00

6 Zack, Jon 0 0 0 0 0.00 0 0.00

7Garett, Garett, Daniel, Kevin 0 0 0 0 0.00 0 0.00

8Emily, Rachel, Sherry, Brianna, Ashley 0 0 0 0 0.00 0 0.00

9 Becky, Brianna C. , Kilee 0 0 0 0 0.00 0 0.00

10 Billy, Divet 0 0 0 0 0.00 0 0.00

11

Bibliography

http://en.wikipedia.org/wiki/Trebuchet

http://www.trebuchet.com/

http://www.tbullock.com/trebuchet.html

Gurstelle, William The Art of trebuchet, Chicago Review Press 2004

Trebuchet

• Extra Credit

• Kilt – 10 point

• Hit the Monster – 10

• Crazy Hat – 10 (has to really be good)

• Over 10 meters (32 Feet) – 2 points for every meter ( 3.2808 feet) over.