How a Trebuchet works

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How a Trebuchet works
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Introduction

• A trebuchet is a medieval siege engine, a weapon
  employed either to batter masonry or to throw
  projectiles over walls. Trebuchets can launch
  objects from 500 to 1,000 feet.

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History

• The trebuchet is thought to have been invented in
  China between the 5th and 3rd centuries BC. The
  device reached Europe around 500 AD.

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How it works

• A trebuchet is powered by a falling
  counterweight acting through a beam acting as a
  lever. The trebuchet is cocked by raising the
  counterweight. A trigger mechanism holds the
  counterweight up. When the trigger is released,
  the counterweight falls and the beam pulls the
  sling.
• Soon after, the sling lifts off and whips in an
  arc upwards. When the projectile moves close to
  the point where the sling makes about a 45 angle
  with the horizontal, the free end of the sling
  slips from the hook, and the missile flies free
  toward its target.

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Step 1

• 1. The counterweight is upright, locked, and the
  trebuchet is ready to fire.

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Step 2

• 2. The counterweight is falling and pulling the
  lever arm and sling upwards.

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Step 3

• 3. The counterweight is falling and pulling the
  lever arm and sling upwards.

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Steps 4 and 5

• 4-5. The sling makes about a 45 angle with the
  horizontal, the free end of the sling slips from
  the hook, and the missile flies free toward its
  target.

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Video

• Trebuchet YouTube

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Physics of a Trebuchet
To find the range of a Trebuchet consider a
projectile fired on a horizontal plane that has a
velocity vo at an angle a with respect to the
horizontal. It will have a range given by
sin 45 cos 45 ½, which cancels out the 2.
Resulting in the range being equal to the
velocity2 divided by gravity.
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Other Physics to consider

• Torque - During the movement of the trebuchet, it
  will experience a torque due to the unbalanced
  weights.
• The moment of inertia about the axle is simply
• Conservation of Energy
• Potential Energy mgh1/2mv2Kinetic Energy

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Trebuchet links

• Trebuchet Size Calculator
• http//www.virtualtrebuchet.com/
• Trebuchet Game
• http//www.globalspec.com/trebuchet/

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THE END