Catapults SCIENCE FAIR 2015
Purpose The reason we did this project would be: to see, out of the 6 th grade class, what group can build a catapult to launch a plastic Easter egg the farthest.
Hypothesis We think that our catapult will launch the egg the farthest because when we pull our arm back over the board, it will give it momentum to shoot the egg farther.
Materials 2 blocks of white pine wood measuring 4x3½x¾ each 1 block of white pine wood measuring 7¾ x4½x¾ 9 drywall screws 1 small wood screw 1 large pencil that is 5½ inches long 1 piece of white pine wood measuring 28x1¾x¼ Approximately 2 feet of orange baling twine Rubbermaid plastic disposable cup 1 plastic Easter egg 1 piece of white pine wood measuring 2½x1x¾ 2 blocks of white pine wood measuring 1½x1½x¾ 1 Crayola green marker 1 Crayola brown marker 1 tape measure
Procedure 1. We got a piece of white pine wood that measured 2½x1x¾ to use as our base. 2. We cut, using a Dewalt 18 volt table saw, a piece of white of white pine wood that measured 28x1¾x¾ to use as our “arm.” 3. Using 2 drywall screws, we installed two blocks of white pine wood measuring 1½x1½x¾ each to the bottom of the “arm” to form center hinge blocks. 4. Using a Dewalt 18 volt drill and a 13/32 drill bit we lined up the 2 blocks and drilled a hole in both. 5. Using a Dewalt 18 volt table saw, we cut 2 blocks of white pine wood measuring 4x3½x¾ each to use as our outer hinge blocks. 6. We used a Dewalt 18 volt drill and a 13/32 bit to drill holes in the 2 outer hinge blocks after lining them up.
Procedure- continued 7. We installed the two blocks from step 5 into one of the ends of the base. We installed them approximately 2 inches apart from each other using a drywall screw each. 8. We lined up the holes in the blocks from step 3 with the holes in the blocks from step 5 and put a large pencil that measures 5½ inches into the holes to form a hinge pin to keep the catapult together. 9. We cut a piece of white pine wood measuring 7¾x4½x¾ with an angle at one end. 10. We installed the piece from step 9 using 2 drywall screws going through the bottom of the board.(slanted side goes down) 11. We cut a piece of orange baling twine that was approximately 2 feet long using a Dewalt pocket knife.
Procedure- continued 12. We cut a notch on each side of the arm that was about 11 inches from the end that is hinged down. 13. We tied one end of the twine into the notches. 14. We drilled a drywall screw into the middle of the board.] 15. We tied the other end of the twine to the screw to form a stopper for the arm. 16. We got a Rubbermaid disposable cup. 17. Using a small wood screw, we screwed the cup to the end of the arm that is not hinged. 18. We colored it camo using the Crayola green and brown markers.
Procedure-continued 19. We put the plastic egg into the cup. 20. We pulled down on the end with the cup on it 21. We let go and watched the egg fly. 22. We measured how far it went and repeated it 2 more times.
Results
Conclusion On our catapult, we had a long arm which helped to propel the egg farther and we had a strong wooden surface that helped to keep it level so it did not tip back and forth. We also had a strong hinge pin and strong hinge blocks to help hold the whole thing together and the entire thing was made out of wood so it was basically all strong. The one thing that needed to be different would be that our arm was not quite strong enough. If we were to do this experiment again, we might use an arm that was thicker so that if would not break as easily. Our hypothesis was halfway correct because I think if it would have not broken, it would have went farther the third time.
Acknowledgements We would like to thank Cassi and her family for providing the supplies, Mrs. Larsen for allowing us the time to work on this project, and the teachers for judging our project. We had a great time and we had a great catapult.