Some physics of trick roping

Trick roping and physics are revealed as being more or less the same thing (One of the revealers won an Ig Nobel Prize several years ago for revealing the reason spaghetti breaks into interesting pieces). James Morgan reports for BBC News:

By studying trick roping as a science, a French physicist has taught himself to lasso like a rodeo veteran. Anyone can teach themselves the famous “flat loop” by following some basic formulae, says Dr Pierre-Thomas Brun, of EPFL in Switzerland. He showed off his ‘cowboy physics’ skills at the American Physical Society meeting in Denver….

But while these loops spellbind our imagination, they also harbour useful mathematical secrets. “Elastic threads are everywhere in our daily lives – from hair and textile yarns to DNA and undersea broadband cables. Even the honey you pour on your toast,” said Dr Brun who worked on the research with his colleagues, Dr Basile Audoly and Dr Neil Ribe….

That Basile Audoly is the same Basile Audoly who shared the 2006 Ig Nobel Prize for physics with his colleague Sebastien Neukirch of the Université Pierre et Marie Curie,  Paris. They were honored  for their insights into why, when you bend dry spaghetti, it often breaks into more than two pieces. [REFERENCE: "Fragmentation of Rods by Cascading Cracks: Why Spaghetti Does Not Break in Half," Basile Audoly and Sebastien Neukirch, Physical Review Letters, vol. 95, no. 9, August 26, 2005, pp. 95505-1 to 95505-1.]

Pierre-Thomas Brun and Basile Audoly have a lasso-physics paper in prep. Meanwhile, the trick-roping paper that Brun presented at the American Physical Society Meeting in Denver is

The mechanics of trick roping.” The abstract explains:

“Trick roping evolved from humble origins as a cattle-catching tool into a sport that delights audiences the world over with its complex patterns or ‘tricks,’ such as the Merry-Go-Round , the Wedding-Ring, the Spoke-Jumping, the Texas Skip… Its implement is the lasso, a length of rope with a small loop (‘honda‘) at one end through which the other end is passed to form a large loop. Here, we study the physics of the simplest rope trick, the Flat Loop, in which the motion of the lasso is forced by a uniform circular motion of the cowboy’s/cowgirl’s hand in a horizontal plane. To avoid accumulating twist in the rope, the cowboy/cowgirl rolls it between his/her thumb and forefinger while spinning it. The configuration of the rope is stationary in a reference frame that rotates with the hand. Exploiting this fact we derive a dynamical ‘string’ model in which line tension is balanced by the centrifugal force and the rope’s weight. Using a numerical continuation method, we calculate the steady shapes of a lasso with a fixed honda, examine their stability, and determine a bifurcation diagram exhibiting coat-hanger shapes and whirling modes in addition to  at loops. We then extend the model to a honda with finite sliding friction by using matched asymptotic expansions to determine the structure of the boundary layer where bending forces are significant, thereby obtaining a macroscopic criterion for frictional sliding of the honda. We compare our theoretical results with high-speed videos of a professional trick roper and experiments performed using a laboratory ‘robo-cowboy.’ Finally, we conclude with a practical guidance on how to spin a lasso in the air based on the results of our analysis.”

(Thanks to investigator Neil Judell for bringing this to our attention.)

BONUS:  Some physics of some toys, as described at that same physics meeting:

Snap, crack and pop: What elastic instabilities in toys can teach us,” Dominic Vella [University of Oxford], abstract for an Invited Paper for the March 2014 Meeting of the American Physical Society, The author writes:

“The mechanism of many modern toys rely on some form or other of elastic instability, from the locomotion of the ‘Hexbug nano‘ to the snapping of a ‘Hopper popper.’ In this talk I will discuss some fundamental mechanical problems that are inspired by the mechanism of such toys. A particular focus will be on the ‘snap’ and ‘pop’ phases of the Hopper popper but I will also discuss the ‘crack’ of a whip and other examples of dynamic elastic instabilities.”