Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists Find that Size Matters When Initiating an Object's Movement Through Grains

30.09.2008
A team of Penn State physicists has discovered that the size of grains, such as sand grains, under which an object is buried is important in determining the force required to begin raising the object.

No one, until now, has discovered how much force is required to initiate an object's movement through grains. The result may be useful for engineering foundations for objects to be anchored in sandy soils, such as power-line towers, or for designing industrial mixer blades, such as those used in pharmaceutical processing. The team's paper is published this month in the journal Physical Review Letters.

"We found that less force is needed to lift an object that is buried beneath small grains than is needed to lift an object that is buried beneath larger grains," said Peter Schiffer, associate vice president for research and a professor of physics at Penn State. "Basically, if you are buried alive and you have to push open a coffin lid, it’s better to be buried under fine-grained sand than under pebbles," he said.

According to Schiffer, other researchers have examined how much force is required to maintain an object's movement through grains, but no one previously had looked at how much force is required to initiate it. "The two measurements are different," he said. "When initiating the movement of an object, the grains immediately above the object must be shifted out of the way to make space for the object to move, which requires that the surrounding grains be loosened. In contrast, an object that already is in motion requires less force to maintain that motion because the surrounding grains are already loosened. It’s the loosening of grains around the object that seems to make the difference," said Schiffer.

The scientists built an apparatus that measures the force required to push a flat circular plate upward from the bottom of a cylindrical bucket that is filled with glass beads. The team measured the force using different sizes of glass beads and found that the smallest beads required the least amount of force to lift the plate. "The total weight of the grains above the plate was adjusted so that it was the same regardless of grain size," said Dan Costantino, a Penn State graduate student and one of the paper's lead author.

In the future, the team plans to measure the force required to initiate the horizontal movement of an object through grains. They also plan to substitute water or a heavy liquid for the air in between the grains. "A liquid that has the same density as the grains will effectively make the grains weightless, so we can further investigate whether the strength of grains comes from their weight or from the way they are packaged together," said Costantino.

This research was supported by NASA and the National Science Foundation.
Sara LaJeunesse
CONTACTS
Peter Schiffer: (+1) 814-863-9658, pes12@psu.edu
Dan Costantino: (+1) 814-865-7260, djc321@psu.edu
Barbara Kennedy (PIO): 814-863-4682, science@psu.edu

Barbara K. Kennedy | EurekAlert!
Further information:
http://www.psu.edu
http://www.science.psu.edu/alert/Schiffer9-2008.htm

More articles from Physics and Astronomy:

nachricht Rapid water formation in diffuse interstellar clouds
25.06.2018 | Max-Planck-Institut für Kernphysik

nachricht When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany

25.06.2018 | Ecology, The Environment and Conservation

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>