The Effects of Initial Conditions on the Motion of the ... › physics › files › 2014 › 08 ›...
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The Effects of Initial Conditions on the Motion of the Boleadora Weapon Jacob Brooks and Aaron Titus, Department of Chemistry and Physics, High Point University, High Point, NC Abstract The effect of the throwing technique on the mo- tion of a thrown boleadora from the point of the boleadora’s release to its full equidistant spread was investigated. The boleadora is an an- cient hunting weapon made of three individual masses connected by rope to a common center point. When the weapon is thrown, the three masses initially travel together. Shortly after re- lease, the masses spread out around their com- mon center point, eventually ensnaring their tar- get. A computational model was developed and compared to actual results measured with video analysis. In one case, the bola was thrown from the knot, and in the other case the bola was thrown from one of the masses. Both the model and results from video analysis are presented. A gaucho throwing a boleadora. Throwing Techniques Boleadora thrown from knot. Boleadora thrown from ball. Video Analyses To fabricate the boleadora, we attached a set of three equally massive spheres with holes drilled through their centers to Berkley Trilene Big Game Fishing Line with a breaking tension of forty pounds (about 178 N). Traditional boleadora and fabricated boleadora. We outfitted the boleadora with infrared reflective markers on each mass and recorded data about the boleadora’s flight using fourteen Raptor-12 in- frared cameras spaced as shown below. The data was used to recreate visualizations of actual throws in VPython. Throwing and tracking the boleadora. Raptor-12 infrared camera. Results & Computational Model The boleadora, when thrown by holding the com- mon point, did not actually spin as one might ex- pect. Rather, the masses slowly spread as the sys- tem was in flight. Boleadora thrown from knot. The second technique of throwing from a mass re- vealed a clear rotational behavior in the system af- ter release. Boleadora thrown from ball. Future Work In the future, we will investigate the behavior of the boleadora with more than three spheres and with different initial conditions. Furthermore, we will investigate the affect of mass and string length on the flight and dynamics of the bola. In addition, the computational models will be refined. In the current models, the strings are treated as very stiff springs and the spheres do not collide. While being swung, it is expected that the spheres will collide and eventually rest against each other, yet the current computational models allow the spheres to pass through each other and oscillate back and forth before they are released. In future models, collisions between spheres will be added. Finally, the photo of the gaucho shows some initial spread in the bola, which was not evident in the video analysis data. After computational models are edited to included non-uniform circular motion, various throwing motions will be investigated to see if the bola spreads during the throw, before it is released. References • VPython Software. (www.vpython.org) • Motion Analysis Software. (www.motionanalysis.com) • D. L. Mathieson, “Wrap up rotational motion by throwing a bola,” Phys. Teach. 30, 180–181 (March 1992). • T. McCarthy, “Bola Motion,” Phys. Teach. 48, 222-224 (April 2010). Acknowledgments • Briana Fiser • Kevin Ford, Taylor Wimbish, and Danielle Paul at High Point University for assistance with the motion capture system in the Human Biome- chanics and Physiology Lab.
Transcript of The Effects of Initial Conditions on the Motion of the ... › physics › files › 2014 › 08 ›...
The Effects of Initial Conditions on the Motion of the Boleadora WeaponJacob Brooks and Aaron Titus, Department of Chemistry and Physics, High Point University, High Point, NC
AbstractThe effect of the throwing technique on the mo-tion of a thrown boleadora from the point ofthe boleadora’s release to its full equidistantspread was investigated. The boleadora is an an-cient hunting weapon made of three individualmasses connected by rope to a common centerpoint. When the weapon is thrown, the threemasses initially travel together. Shortly after re-lease, the masses spread out around their com-mon center point, eventually ensnaring their tar-get. A computational model was developed andcompared to actual results measured with videoanalysis. In one case, the bola was thrown fromthe knot, and in the other case the bola wasthrown from one of the masses. Both the modeland results from video analysis are presented.
A gaucho throwing a boleadora.
Throwing Techniques
Boleadora thrown from knot.
Boleadora thrown from ball.
Video AnalysesTo fabricate the boleadora, we attached a set ofthree equally massive spheres with holes drilledthrough their centers to Berkley Trilene Big GameFishing Line with a breaking tension of fortypounds (about 178 N).
Traditional boleadora and fabricated boleadora.
We outfitted the boleadora with infrared reflectivemarkers on each mass and recorded data aboutthe boleadora’s flight using fourteen Raptor-12 in-frared cameras spaced as shown below. The datawas used to recreate visualizations of actual throwsin VPython.
Throwing and tracking the boleadora.
Raptor-12 infrared camera.
Results & Computational ModelThe boleadora, when thrown by holding the com-mon point, did not actually spin as one might ex-pect. Rather, the masses slowly spread as the sys-tem was in flight.
Boleadora thrown from knot.
The second technique of throwing from a mass re-vealed a clear rotational behavior in the system af-ter release.
Boleadora thrown from ball.
Future WorkIn the future, we will investigate the behavior ofthe boleadora with more than three spheres andwith different initial conditions. Furthermore,we will investigate the affect of mass and stringlength on the flight and dynamics of the bola.
In addition, the computational models will berefined. In the current models, the strings aretreated as very stiff springs and the spheres donot collide. While being swung, it is expectedthat the spheres will collide and eventually restagainst each other, yet the current computationalmodels allow the spheres to pass through eachother and oscillate back and forth before they arereleased. In future models, collisions betweenspheres will be added.
Finally, the photo of the gaucho shows someinitial spread in the bola, which was not evidentin the video analysis data. After computationalmodels are edited to included non-uniformcircular motion, various throwing motions willbe investigated to see if the bola spreads duringthe throw, before it is released.
References•VPython Software.
(www.vpython.org)
•Motion Analysis Software.(www.motionanalysis.com)
•D. L. Mathieson, “Wrap up rotational motionby throwing a bola,” Phys. Teach. 30, 180–181(March 1992).
•T. McCarthy, “Bola Motion,” Phys. Teach. 48,222-224 (April 2010).
Acknowledgments•Briana Fiser•Kevin Ford, Taylor Wimbish, and Danielle Paul
at High Point University for assistance with themotion capture system in the Human Biome-chanics and Physiology Lab.
