downloaded from http://cmse.olemiss.edu/files/2011/11/catapult.pdf on 10/26/2014
adapted by Mark Whipple
Building a Catapult
Step 1: Decide how your catapult will store energy
A catapult is a mechanism that takes potential energy and turns it into kinetic energy. It
does this by storing energy in twisted rope, a spring, or something elastic (like a rubber
band). With your given materials, you must decide what devices, or combination of
devices will power your catapult.
Go through the available materials and list different ways that your catapult
can store energy. Now, discuss with your group which mechanism you think will give you the greatest accuracy and power in the launching of an object about the size of a ping-pong ball weighing about 30 to 40 grams (Note: for SMS students the weight will be approximately 4.5 grams). Then, as a group, decide how your catapult will store energy.
Step 2: Controlling and adjusting power (Optional for SMS students)
Your catapult must be able to fire accurately. Therefore, you must be able to change
something on your catapult so that it can fire the hackysack shorter or longer distances
depending on what is needed. How will your group’s catapult be able to adjust for
Step 3: Design a trigger (Optional for SMS Students)
Your catapult must have a trigger or type of switch to operate (a person can only be
responsible for releasing the trigger)
Step 4: Designing the body of the catapult
What materials will hold your mechanism? How will you keep your catapult steady?
How will you hold the projectile?
Take each persons designs and as a group, choose which designs to incorporate in your
catapult . Draw your design and include labels for your launching mechanism, your power adjustment mechanism, and your trigger.
Step 5: Building and Testing your catapult
After building your catapult, practice firing projectiles to see how much control your
machine has. YOU MUST ASK A TEACHER TO ASSIST YOU BEFORE TEST
FIRING YOUR CATAPULT. After testing, make adjustments if necessary.
Step 6: Competition
Each group will have two opportunities to fire the projectile as far
as possible. The final rankings will take both attempts into account. May the best catapult win.