Foam Catapult

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In this project I created a catapult out of foam boards to test its ability to project five projectiles. I tested the catapult out on five different projectiles: a small chocolate weighing 8 grams, a ping pong ball weighing 2.7 grams, a small tennis ball weighing 43 grams, a regular tennis ball weighing 72 grams, and a clementine weighing 78 grams. For each projectile I conducted three trials and collected how far the projectile traveled and how long it took to travel that distance. With that information I was able to create tables and graphs to visualize the speed of each trial to determine how precise or accurate the catapult was.

Supplies

- Foam core (somewhere around a 1.5 meter by 1.5 meter board)

- Knife/ scissors

- Duct Tape

- Two thick wood dowels (1.5 cm wide x 30 cm)

- 4 large rubber bands

- Measuring tape

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Use knife to cut 2 triangles ( 53 cm, 27 cm, 59 cm) out of the foam

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Cut a rectangle (37 cm by 13 cm and 2 cm wide)

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On the bottom of the longer leg of the triangle cut a 13 cm by 2 cm vertical rectangle 1 cm in from the side (do on both triangles)

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Slide the rectangle from step 2 into the slits that were just made so that it helps hold the triangles together

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Take the larger wooden dowel and poke a hole 5 cm drown from the top (being careful not to break the foam anywhere else) (do on both triangles)

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4 cm from the rectangle slit and 5 cm up from the bottle poke another hole with the dowl (do on both triangles)

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Cut out strips with the measurements seen to the right (2 of each)

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Duck Take the parts together so that they connect to the triangles (see in picture to the right)

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Cut a rectangle 25 cm by 6 cm and duct tape it so that it lays in between the legs we just made in the previous step (this should complete the base)

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Cut a 61.5 cm by 10 cm rectangle from the foam. 3 cm from the bottom work a dowel through (leaving a little room so it doesn't rip through)

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At the other end of the arm shave out a box (leaving a bottom) so that you are able to insert projectiles

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Slide a dowel through the top holes (before putting through the second hole add the rubber bands (fold one rubber band in half and loop it through another rubber band, add the folded rubber band side through the dowel)

Add the other dowel through the bottom holes (before sliding through the other hole put the rectangle arm through it too)

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Pull the other sides of the rubber bands over and onto the arm of the catapult

(Optional)

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Optional: Cut two 6 cm by 9 cm rectangles out of foam and cut out a semi circle on one side and duct tape it onto the base in between the legs. This will act as a release so that when you are able to pull the arm back to slide a rod into the semicircles to hold down while you load the catapult. When you are ready you pull the rod out, allowing the arm to move forward to project the item.