If it is lighter, is it farther?

Project by Onyea Sholty2009

Gravity

Gravity is the net force exerted by the Earth on objects in its vicinity. Gravity makes things fall. I built a catapult to see how far things go depending on their weight. My catapult will demonstrate how things that have different weights can travel different distances.

History of gravitational theory

The first serious gravitational theory began with Galileo Galilei in the late 16th and early 17th centuries. In his famous experiment dropping balls from the Tower of Pisa, and later with of balls rolling down inclines, Galileo showed that gravity accelerates all objects at the same rate. Galileo correctly used air resistance as the reason that lighter objects may fall more slowly in an atmosphere. Galileo's work set the stage for Newton's theory of gravity.

My Catapult

• After finding plans online for a large catapult I started cutting PVC pipes and glued them with the joints and bolted it together

at the shop.

• Tools• Electric drill• ½” drill bit• 25/64” drill bit• 9/32” drill bit• Saw• Miter box• 4” or larger C-clamps (3-4)• Scrap wood• Materials• Note: All pipes and fittings are schedule 40 ABS or PVC pipe,

1½” in diameter. PVC is usually white. ABS is typically black. We used ABS but either will work.

• 10’ long pipe (5)• End cap fittings (4)• Threaded pipe unions (4)• Coupling• 90° elbow fittings (4)• Tee fittings (2)• Pieces of garden hose, ½” inside diameter, 1” long (2)• ½” diameter, fully threaded bolt or threaded rod, 8” long,

nuts and washers • ¼” bolt, 2” long, washers and nuts• 3/8” diameter bolt, 5” long, washers and nuts (4)• Cement appropriate for the type of plastic used• Estimated Cost: Under $75.

Human Powered TrebuchetThis is the proposed outcome. First you load the catapult with the items. Then you push down the throwing arm and the long end will swing over

and launch my pre-weighed items.

My Demonstration

• I am going to be throwing one broom handle, one water balloon, and two marshmallows.

• Weight of broom handle: 3 oz• Weight of water balloon: 9 oz• Weight of two marshmallows: 0.01 oz• My hypothesis is that if things are heavier,

they will go farther.

Getting Ready to Launch!!

Get Ready, Set, Go!!

Fire!! Broom & Marshmallows

Results of Demonstration

• Distance of broom handle flight: 71 feet• Distance of water balloon flight: 33 feet• Distance of marshmallow flight: 26 feet

• My hypothesis was wrong. The heavier it was, the higher it went, but didn’t go so far. The broom handle was the middle weight and it flew the farthest.

Sources of Information

• http://cdn.oreilly.com/make/television/trebuchet.pdf

• http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-what-is-gravity.html

• http://en.wikipedia.org/wiki/Gravity• http://www.youtube.com/watch?

v=Z5BDARpBcz8&feature=PlayList&p=968A78234EE56D32&playnext=1&playnext_from=PL&index=10

Acknowledgements

• I would like to thank Home Depot, Camron’s Plumbing and Heating, Bob Peterson, Malonie Vance, Eric Lambert, Darcy Ervin, Wendy Ervin, and Maren Ervin for helping me.