Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Maths cracks egg flip

28.03.2002


Friction pushes a spinning egg from horizontal to vertical.



Mathematicians have cracked the conundrum of the spinning egg. A hard-boiled egg spun on its side flips upright because of friction between the egg and the table, they calculate1.

The egg’s elevation appears paradoxical. Its centre of gravity moves up - making the system seem to be gaining energy.


In fact, spinning energy, translated into a horizontal force, pushes the egg upright, say Keith Moffatt of the , Japan.

"The egg sacrifices spin energy to achieve its rise," says Moffatt. A twirled raw egg doesn’t rise because its liquid centre soaks up spinning energy from the shell, stopping it powering the egg’s ascent.

There would be no horizontal force on a perfectly smooth table, the duo point out. But neither must the surface grip the egg too much. The egg ascends in jerks, not a smooth roll.

"You have to have slipping between the egg and the surface," advises Moffatt. "If you tried this on a hard rubber table it wouldn’t rise."

"Friction is absolutely crucial," agrees physicist Bernie Nickel of the University of Guelph in Canada. Nickel has analysed the physics of the ’tippe-top’, a mushroom-shaped toy that flips from spinning on its round end to its stalk. "The egg is a rather more complicated shape," he says.

Understanding the dynamics of rotating objects is a fundamental problem. Spacecraft engineers, for example, need to know how their creations will spin in the void. But Moffatt cautions that the egg’s interaction with the surface underneath it makes it dangerous to extrapolate to zero gravity.

In a spin

There is a critical spinning speed below which the egg stays horizontal. This is about ten revolutions per second - roughly the speed it reaches after a firm flick of the wrist.

As the egg rises, its spinning form is more compact, making it whirl more quickly. "It’s like when a turning figure-skater speeds up by pulling in his or her arms," Nickel says.

The egg’s initial orientation doesn’t matter, and it will pirouette on either pole. "I think it prefers to go up on the sharper end," Moffatt speculates.

References
  1. Moffatt, H.K. & Shimomura, Y. Spinning eggs - a paradox resolved. Nature, 416, 385 - 386, (2002).

JOHN WHITFIELD | © Nature News Service

More articles from Interdisciplinary Research:

nachricht Easier Diagnosis of Esophageal Cancer
06.03.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Sandia uses confined nanoparticles to improve hydrogen storage materials performance
27.02.2017 | DOE/Sandia National Laboratories

All articles from Interdisciplinary Research >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>