Warm Up

•What is the engineering design process and how does it help us?

Conquer the CastleMrs. Duff

Woodstock Middle School

What is a “catapult”?

• a device in which accumulated tension is suddenly released to hurl an object some distance, in particular.

• There are three primary technologies that fall into the "catapult" category.

• Catapult

• Ballista

• Trebuchet

Catapult

• the winched-down bucket that people normally think about when they hear the word "catapult“

Ballista

• A very large crossbow

Trebuchet

• is a weighted beam that swings a sling carrying the projectile

How do they work?

• Both catapults and ballistas work by storing tension either in twisted ropes or in a flexed piece of wood

• A trebuchet consists simply of a pivoting beam and a counterweight that rotates the beam through an arc.

Define the problem

• You are medieval knights. The king has presented you with a great quest to attack and seize a nearby castle. If you complete the quest you will presented with great riches and live a lavish life. If you fail the quest you will be beheaded in the inner ward for all the community to watch.

The ChallengeDesign, construct, test, and evaluate a catapult that will project a boulder (a jumbo marshmallow) over the moat and outer curtain of the castle and hit and destroy the inner curtain (a wall of aluminum cans).

• Design Specifications and Constraints:

• The device:

• Must be safe to use

• Must be constructed by the group

• Must launch the marshmallow with nothing attached to it

• Must not destroy the marshmallow and leave it in its original shape

• Must be constructed only of the materials provided

• The base of the catapult must be no larger than 10” x 10”

• The marshmallow must be launched using a simple machine

• Students will:

• Work in teams of two or three

• Complete all of the documentation before construction begins

• Follow the rules and procedures of the lab

• The competition:

• Students will get three chances to know down the inner curtain wall

• The device must be behind the launch line at the time of launching

• The marshmallow must project over the moat and outer curtain wall before destroying the inner curtain wall.

• In order to compete, your device must meet all the specifications and constraints.

• During competition only the members of the team testing will be allowed out of their seats.

Materials

• On the lines provided, write what part of the “catapult” each material could be used for. (tension, frame/pivot beam, bucket, projectile)

• Integral: Non-integral:

• 10 craft sticks _______________ Ruler

• 4 notched craft sticks ______________ Scissors (do not use to cut craft sticks)

• 5 assorted size rubber bands _______________ 1 jumbo marshmallow _____________

• 1 plastic spoon _______________ 1 sheet of sand paper

• 24” masking tape _______________

• 1 jumbo craft stick ____________

Today’s Tasks1.Complete the Research and Investigation questions in the packet.

2.Label uses for the materials in the materials list.

3.Each person sketches a possible solution for the catapult. These must be detailed. Label materials and describe how it works. List the strengths/pros and the weaknesses/cons of your idea.

4.Discuss the brainstorming ideas and choose one or combine ideas for your final solution. You must show me your sketches and explain your solution to me prior to receiving materials.

5.Get your materials and “tools” and begin construction. Write your names on your paper bag.

6.Clean up. Place materials back in bag and return them to me. Return tools and throw out trash.

7.Return to the discussion area.

Helpful Links

• http://beam.berkeley.edu/sites/default/files/Mini%20Catapults%20Lesson.pdf

• http://tinyscreenfuls.com/2006/04/craft-stick-catapult/

• http://www.stormthecastle.com/catapult/popsiclestick-catapult.htm

• http://www.devincollier.com/how-to-build-a-simple-small-marshmallow-catapult/

• http://www.superchargedscience.com/science-catapults.htm

• http://www.ehow.com/how_6393127_directions-make-mini-catapults.html