Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
×

Comment Re:Doesn't Gravity Affect Angle of Repose? (Score 3, Informative) 51

Astrophysicists my ass... Geologists have this covered! From "Static and dynamic angles of repose in loose granular materials under reduced gravity"
http://adsabs.harvard.edu/abs/...

Until now it has been assumed that the angles of repose are independent of gravitational acceleration. The objective of this work is to experimentally determine whether the angles of repose depend on gravity. In 33 parabolic flights in a well-controlled research aircraft we recorded avalanching granular materials in rotating drums at effective gravitational accelerations of 0.1, 0.38 and 1.0 times the terrestrial value. The granular materials varied in particle size and rounding and had air or water as interstitial fluid. Materials with angular grains had time-averaged angles of about 40 degrees and with rounded grains about 25 degrees for all effective gravitational accelerations, except the finest glass beads in air, which was explained by static electricity. For all materials, the static angle of repose increases about 5 degrees with reduced gravity, whereas the dynamic angle decreases with about 10 degrees. Consequently, the avalanche size increases with reduced gravity.

Comment Re:Lobbying aside (Score 5, Interesting) 423

In some cases, it can pay off. I ended up getting around ~$800 back from the feds this year and through a deal on Amazon, I got 10% bonus by getting the refund back in Amazon gift credit. That's a free 80 bucks, well better than any tiny interest rate I could have gotten in a savings account. When the interest rate you can get is higher than the rate of inflation, you might have a point...

Comment Re:Not the first time this has happened (Score 1) 642

Well governed? Did you watch the show? Starfleet command and the general Federation council decisions being total stupidity are the basis for several episodes and even entire arching plotlines in the series. It's especially true in DS9 where government idiocy goes to a whole new level.

Comment Re:Permanent Habitat? (Score 1) 100

Spectacular radiation shield? You mean a lot of water? If we are melting water at the surface, it might be feasible to melt water, pump it over the habitat, and allow it to form an ice radiation shield over the habitat. Think like a big radiation blocking igloo... All it takes it a lot of energy, but if we get fusion figured out, you'll have all the fuel you need on Europa!

Slashdot Top Deals

"Spock, did you see the looks on their faces?" "Yes, Captain, a sort of vacant contentment."

Working...