How to Design a Small Catapult or Trebuchet

Catapult Activity

Problem:

You are to design and create a catapult like device that will launch a mini marshmallow into a bucket at a designated distance with accuracy.

Design your device by sketching out a drawing.
Create the device.
Test the device by using it.
Compete for distance with other catapults.

Materials You Need to Have in Class by Thursday:: one-cup milk carton, scissors, two 2-inch rubber band and other rubber band sizes as needed or wanted (you will find you get different distances depending on the size of the rubber band, try out different sizes! , toothpick, 2 pencils, tape, small match box (can be made from a 3 by 5 card and tape).

Materials I Will Provide for Wednesday: mini marshmallows, graph paper, extra rubber bands.

Catapults will be launched Monday in the hallway, have them ready! You will receive a 100% if the marshmallow goes FORWARD...regardless of the distance. There will be a target to aim for. Any group that hits the target will receive extra credit. Each group has 3 shots.

Considerations:

You may use other materials from home as discussed in class. Remember to allow for easy rubber band attachment..

Step One: Sketch or draw your device. As you sketch, new ideas will come to you. You may wish to do your rough work on scratch paper.

Step Two: Build your design.

Step Three: Test your device. First unloaded, then loaded.

You may use ANY DESIGN you wish! Search the internet/books for one that you think will work. Below is a simple design that uses items found around a house. You may use the design if you wish or combine the ideas with something else that your group might find.

Procedure: (see diagrams below)

Materials You Need to Have in Class by Friday: one-cup milk carton, scissors, two 2-inch rubber band and other rubber band sizes as needed or wanted (you will find you get different distances depending on the size of the rubber band, try out different sizes! , toothpick, 2 pencils, tape, small match box (can be made from a 3 by 5 card and tape).

1. Cut off the top of the milk carton and then cut the carton as show in diagram 1. Cut holes the size of a pencil in both sides and in the back.
2. Push a rubber band through the hole in the back and hold it in place with a toothpick. Push a pencil through the holes in the sides.
3. Cut the tray of a match box in half lengthwise. If you don't have a matchbox make one of a 3 by 5 card and tape. Using tape, attach the box to the sharpened end of the second pencil with the pencil to the outside.
4. Select one of the three rubber bands to complete the remainder of the procedure.
5. Lay the pencil across the other with the eraser end facing the front of the catapult. Loop the rubber band over the eraser end. Fold the front flap of the milk carton in, crease it, and tape it down.
6. Do a trial test of your catapult to make sure it works properly. Place a marshmallow in the holder, pull back the pencil, an then release. Make any adjustments needed, and modifications to make the catapult work better.
7. On your data, make a sketch of your catapult and the results of your throws.

Data:

(your drawing)

throws: 1_______________ 2_______________ 3_______________

Try destroying a castle using an computer animated version of a trebuchet:

http://www.pbs.org/wgbh/nova/lostempires/trebuchet/destroy.html

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