Observe - Making a Lever Work for You

Levers can provide an advantage by adjusting effort force and fulcrum position.

A wonderful example of a lever is the trebuchet.  In the middle ages during wars, armies used the trebuchet to throw big rocks or balls of flaming materials at enemies or their castles.
Load
The load is the object the trebuchet throws. In the old days, it was usually something very heavy. A large rock could do a lot of damage when it hit a castle!
Tell me more - Load

More Levers
The effort force weight must be lifted high in the air before the trebuchet can work. This is done with ropes attached to small levers that pull the load side of the lever down, which can raise the effort force weight high in the air. The trebuchet then is ready to fire!
Tell me more - More levers

Trebuchet

Click the tell me more buttons to learn more about the Trebuchet
Fulcrum
The trebuchet has a lever arm that is uneven. The side attached to the load is much longer than the side attached to the effort force. A load is placed in a sling, which makes the lever arm even longer. When this lever works, the load side of the lever moves a long way in a short time. This gives the trebuchet a big speed advantage.
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Fulcrum
This is where the lever of the trebuchet pivots. Because the fulcrum is in the middle, a trebuchet is a class 1 lever. Notice that the fulcrum is very close to the effort force. When this lever works, the long part of the lever arm attached to the load moves a long way, and the load must move very fast.
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Effort force
This is what makes the trebuchet lever move. The effort force is a very, very heavy weight that drops. Before the trebuchet can work, this weight must be raised high into the air.
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The catapult is a simpler version of the trebuchet.  Both use a strong effort force and lever with a speed advantage to throw something fast and far.  Can you see the difference between a catapult and a trebuchet?

 Video

Watch this ADLC Digital Lesson on Trebuchets and Catapults

In ancient times, trebuchets and catapults were weapons that did a lot of damage.  How did they work?


 Notebook: How do I adjust a lever to move the load the way I want to?

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  2. Complete the activity using the links provided (in the activity and below).
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