Featured Research

from universities, journals, and other organizations

Physicists Find That Size Matters When Initiating An Object's Movement Through Grains

Date:
October 3, 2008
Source:
Penn State
Summary:
Physicists have discovered that the size of grains, such as sand, above a buried object 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 discovery may be useful for engineering foundations for objects such as power-line towers, or for designing industrial mixer blades, such as those used in pharmaceutical processing.

The researchers filled a cylindrical bucket with glass beads and measured the force required to lift the beads.
Credit: Costantino, Penn State

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.


Story Source:

The above story is based on materials provided by Penn State. Note: Materials may be edited for content and length.


Cite This Page:

Penn State. "Physicists Find That Size Matters When Initiating An Object's Movement Through Grains." ScienceDaily. ScienceDaily, 3 October 2008. <www.sciencedaily.com/releases/2008/09/080926120529.htm>.
Penn State. (2008, October 3). Physicists Find That Size Matters When Initiating An Object's Movement Through Grains. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2008/09/080926120529.htm
Penn State. "Physicists Find That Size Matters When Initiating An Object's Movement Through Grains." ScienceDaily. www.sciencedaily.com/releases/2008/09/080926120529.htm (accessed July 29, 2014).

Share This




More Matter & Energy News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
Powered by NewsLook.com
Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Newsy (July 28, 2014) Stanford University published its findings for a "pure" lithium ion battery that could have our everyday devices and electric cars running longer. Video provided by Newsy
Powered by NewsLook.com
The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins