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### Tapping Subway Trains For Energy

Storing energy in track elevation? (229 comments)

More seriously, I wonder if subways currently store some of that kinetic energy by putting the passenger platforms at a slightly higher elevation (not as deep in the ground) in comparison to the other portions of the track. If I have my math right, the kinetic energy of moving at 30 meters per second ( ~67 miles/hour) is approximately the potential energy of an elevation of 45 meters in 1 Earth gravity (0.5mv^2 = mgh --> 0.5v^2 = gh --> h=0.5v^2/g --> h = 0.5(30m/sec)^2/(10m/sec^2) = 45 m/sec). I imagine that that would be much too rollercoastery for a local train, and you wouldn't want to have the train fly off the track so easily for arriving a little too fast, but it wouldn't surprise me if a dip of a meter or two is engineered into subway lines for a bit of energy savings.

more than 3 years ago
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### Australia's Vast, Scattershot Censorship Blacklist Revealed

They need to weight individual MPs votes by their local approval rating.

Interesting, although the devil is in the details of how approval ratings would be measured.

You might want to consider what other improvements are politically and technically practical. Australia already has a relatively sophisticated vote counting system (instant runoff voting, which is not my favorite, but still pretty good in my opinion). So, perhaps the most universally understandable improvement in responsiveness would come from having more frequent elections. Lowering the stakes in elections and reducing the time that a losing politician needs to wait to run for reelection would encourage them to be slightly more honest in stating their opinions and would give them more accurate feedback about what the public really thinks.

more than 5 years ago
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1 / 26 millionth of Verizon's revenue (579 comments)

Newsgroup feeds use up about 1.5TB a day. Do the math for 14 days retention. It's a heck of a committment.[sic]

1TB 7200RPM hard disks are currently priced at US\$169 on pricewatch.com, with free ground shipping.

1.5TB x \$169/TB = \$253.50/day of retention.
x 14 days = \$3549 per fortnight of retention.

In comparison, Verizon's sales for 2007 were \$94.72 billion, that is, over 26 million times as much. Even if you multiply usenet retention costs by a factor of 10 or 100 to account for multiple copies, other hardware, etc., it is nowhere near even the roundoff accuracy of the financial statements in an shareholders' annual report of a company of that size, not really "a heck of a commitment."

more than 6 years ago

# Slashdot: News for Nerds

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