Sunday, October 7, 2012

Pumpkin Catapults

We're testing the waters for our fun Halloween Themed Science Saturday in the Park and launching candy corn pumpkins via a home made popsicle stick catapult.

I made this catapult lesson for an outreach event for middle school girls.  The main concept: transfer of energy.  Energy is stored as elastic energy (a form of potential energy) when you pull down the catapult arm. When you release, the energy is transferred to kinetic (fancy word for "motion") energy.  If you pull down further, more energy is stored (be careful though, the sticks may snap) and the item should go further and faster in ideal conditions.

J launching a pumpkin
Catapult Assembly:
*Glue or masking tape 4 popsicle/craft sticks together - lay two sticks end-to-end and glue one stick on top so it is glued to both sticks, flip it over and glue one stick on the other side.
****Please use caution when using hot glue around kids.  You can white glue them for a better bond, but you'd have to let them sit/dry overnight.****
*Repeat the stick assembly from above 5 times, so you have 6 total longer sticks.
*Assemble 3 of the longer sticks you just created (from above) to form the base - a triangle (a good and strong shape).  Glue/tape the corners together.
*Take the remaining 3 longer sticks and glue them to each corner and gathering on top (forming a pyramid shape).
*Catapult arm assembly: glue/tape 5 popsicle/craft sticks together three on the bottom, end-to-end and two on top.  Flip over after gluing so the 3 sticks are on top.  Glue a Dixie cup (to go salsa containers can work well too) to one side of the catapult arm.
*Take a rubber band and loop it around the top of one of the catapult sides using a girth hitch knot.
*Stick the arm of the catapult through the rubber band and glue/tape it to one corner of the base (we both glued and taped).
*Stick launching item into the cup, pull back on the catapult arm and release.

Launching items:
*Candy Corn Pumpkins!
*Bite sized candy bars - great because you can launch many times, unwrap and eat
*Gummy fruits
*Uncooked beans
*Small softer toys
Warnings: I don't recommend harder objects like rocks, at least indoors.  Also, make sure the flight path is clear from all faces (including the launcher).  Eat unwrapped, launched candy at your own risk.

Science play ideas:
*How far can you launch your item?
*Try different sized items.  How do they compare?
*Try multiples of the same item.  How do they compare to your first launch of only one of that item?
*Try releasing the catapult arm at different heights.  What happens if you release close to the top of the catapult vs. when you pull it all the way down to the ground?
*Play a game where you hit targets.
*Try different rubber bands (you can always stretch them over the cup to attach to the catapult arm).  How does the rubber band affect your catapult?
*What happens if you don't hold down the front of your catapult while you try to launch your item?

This is what we'll be doing for Science Saturday.  Come join us if you can!  Shoot me an email, and I'll give you more specific details.

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  1. Very cool!

    If we're ever in the Bay Area, we'll come to your Science Saturdays, for sure!

    1. If you're ever planning to be in the Bay Area, let us know and we can try to organize one you can attend!

  2. I love the idea of Science Saturdays. Would you mind sharing how you set this up? I live in Alabama. Thanks.

    1. Sure! I'll write a blog about this in the next few weeks. Thanks :-)