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Physics of Catapulting. By: Andrea Kuchta. Catapults. Defensive and offensive weapons that were used in medieval and primeval warfare before artillery was invented Forerunner of guns Launch projectiles long distances. Items used. 1 Ping- pong ball 1 Plastic spoon 1 elastic (rubber band)
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Physics of Catapulting By: Andrea Kuchta
Catapults • Defensive and offensive weapons that were used in medieval and primeval warfare before artillery was invented • Forerunner of guns • Launch projectiles long distances
Items used • 1 Ping- pong ball • 1 Plastic spoon • 1 elastic (rubber band) • 1 Paper cup • Scotch tape • Coins • 1 Small (full) plastic bottle • 1 small, perfectly round stick of wood
Making A Homemade Catapult • Put 2 aligned holes in the sides of the cup • Be sure they are big enough for the stick (which acts as an axel) to spin freely in • Put change in the cup to weigh it down • Using tape connect the spoon to the stick • Tape the small bottle to the cup between and perpendicular to the holes • Tape the elastic to the top of the small bottle • Using tape connect the elastic to the spoon so it stays put • Place the small piece of wood in the holes
The experiment • Place the ping-pong ball on the spoon • Pull back spoon • Record the angle and release • Mark the landing point and measure the horizontal distance • Repeat steps 1-4 two more times • Place data in data table
What Happened • As I increased the angle of the spoon: • The tension in the elastic increased • Increased the force • The ping-pong ball gained more potential energy • When released: • Potential Energy in the ball was converted to Kinetic Energy • The force created by the tension gave the ball even more energy
The Physics Behind It • The further you pull the lever back the more tension you are creating in the elastic • As you pull the spoon back you are increasing it’s angle • increases the tension in the elastic • The tension in the elastic creates a force which acts upon the ping-pong ball when it is launched • The more tension you create the more energy the ball will be given • Tension and force are equally proportional • Meaning the greater the tension is the greater force acting on the ping-pong ball will be • The force exerted on the ball gives the ball energy
The Physics Behind It (continued) • As you pull the spoon back the ping-pong ball gains potential energy which is converted to kinetic energy when released • The angle and horizontal distance are equally proportional • The greater the angle you launch it at the farther it will travel in the horizontal direction
Bibliography • Works Cited • Dolores Gende: Ap Physics Catapult Project. 7 Feb. 2007 <http://apphysicsb.homestead.com/catapult.html>. • Faughn, Jerry S., and Raymond A. Serway. College Physics. 6th ed. Toronto, Ontario, Canada: Thomson, 2003. • Gurstelle, William. The art of the catapult : build Greek ballistae, Roman onagers, English trebuchets, and more ancient artillery. Chicago, Illinois: Chicago Review, 2004. • “How does a catapult work?” How Stuff Works. 7 Feb. 2007 <http://www.howstuffworks.com/question127.htm>. • Radlinski, Filip. “Principles of motion.” How Stuff Works. 7 Feb. 2007 <http://www.howstuffworks.com/framed.htm?parent=question127.htm&url=http://www.geocities.com/SiliconValley/Park/6461/trebuch.html>.
