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DESTROY THE CASTLE
A Model of a Trebuchet
By
J. Kalinowski
(student)
What is a trebuchet?
• An Medieval war
machine
• A catapult that uses a
counterweight for the
applied force
Copyright www.sca.org.n2/collegium/uni36/medieval_war.html 2002
The Challenge
• Build a wooden trebuchet that will throw a
hackysack at a wooden wall
• The base of the trebuchet should be able
to fit into a square that is 50 centimeters
on each side
• The wall will be placed 3 meters from the
trebuchet
Predictions
• Using the equations for projectile motion the projectile
should be released at a velocity of 3 meters per
second at a height of 0.8 meters
• The sling arm should be longer than the counterweight
arm
• The hackysack should be released in a horizontal
direction
EQUATIONS
•
•
•
•
•
Dx = vix t
Dy = ½ (9.8 m/s2) t2
Torque = F (lever arm)
Ideal mechanical advantage = effort arm/load arm
Actual mechanical advantage = force out/force in
The Design
• The sling arm measured 0.8 meters
• The sling measured 0.5 meters
• The counter balance arm measured 0.4
meters
• The maximum height was 0.75 meters
The Diagram
40 cm
80 cm
75
cm
43 cm
Actual picture
• Picture or movie from
digital camera
Analysis of Trebuchet
• The sling needed to be extended 10 cm to
increase height and speed
• We found that a counterweight of 1.2 kg
gave us the best run
• The base of the trebuchet should be
increased to give more stability
Works Cited
•
•
•
Burke, Dillion Shiel. “Trebuchet picture”. Posted 2001. Accessed 8 Sept
2002 < www.sca.org.n2/collegium/uni36/medieval_war.html>.
Faughn, Jerry and Serway, Raymond, Physics, Holt 2002. Chapter 8
“Rotational Equilibrium and Dynamics”.
Geiselman, Kevin A. “Trebuchet Construction Hints and Tips”. Ingenium –
Ingenious Machines. Revised 27 May 2002. Accessed 25 August 2002
<http://www.tasigh.org/ingenium/hints.html>.