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## Comment Re:Mass and Weight are different (Score 2)78

force equals *mass* times acceleration. ... the acceleration would be the same but the force experienced by Curiosity's tires would be ~3x larger (ignoring any shock absorption).

You do have a point -- I don't agree with some of the other responders who talk about traction forces being smaller as well. Just to make it clear: what you say applies to a cart on wheels, having constant horizontal velocity and approaching a bump in an otherwise flat surface. A larger mass of the cart will result in a larger force at the wheels the moment the cart hits the bump, regardless of gravity.

However, this force is roughly F = m v^2/L, where v is the horizontal velocity of the cart, L is the travel of the suspension, and m is the moving mass. The moving mass can be just a single wheel; in that case L is the leeway in the tire rubber (less than a millimeter), or m can refer to the entire car, with L the travel of the wheel suspension.

Now, the issue of inertia is only relevant if the instantaneous extra force is larger than the gravitational force. Given that this Mars Rover has a maximum speed of 0.025 m/s, the maximum inertia-driven acceleration is about 1 m/s^2, even assuming only 0.5 mm of suspension travel. This is much less than the gravitational acceleration (10 m/s^2); therefore inertia does not make a significant difference in the wear on the wheels.

## Comment Re:So many extra fees (Score 1)91

In Europe ... So no tipping in many places (or minimal tipping) as people get payed by their boss for the work that they do.

You can't generalize that across all of Europe, unless "minimal tipping" means anything less than 15% in a restaurant. Tipping conventions vary quite a bit over Europe (based on the travel guides that I've seen). And for instance, in the UK, the 10% service charge on restaurant bills seems to be optional in some cases, although I don't visit the UK often enough to grasp the substle details here.

## Comment Re:psst... your ignorance is showing (Score 1)1105

Probably you as an AC won't read this two days later, but I don't understand why you changed the subject from "in the 1490's" into the present one, in response to my post. The original subject is a reference to Columbus (that's earlier than Galileo) and in that era the only other Christian church would have been the Eastern Orthodox church.

## Comment Re:So many extra fees (Score 1)91

"you can do the same thing with the European system. On the receipt you just have to break down the advertised 9.95 Euro price into merchandise and taxes."

The national sales tax (VAT, or the local-language equivalent) is always printed on the receipt in the EU. Other taxes that come to mind: tourist tax on hotel stays, which is also printed on the receipt (city-dependent fee, not always listed up-front) and "extra costs" on plane tickets which used to be treacherous but must be included in the ticket price nowadays.

There are special tariffs/duties on things like alcohol and cigarettes, but I've never seen them stated explicitly, not even in an airport duty-free shop.

## Comment Re:In 1490's (Score 1)1105

"official church dogma that this was not true, and this created a climate where openly saying the earth was round was not exactly a safe position to take."

The church dogma wasn't about whether the earth was round ot not, but about whether the sun revolved around the earth or the other way around.

## Comment Re:Title is Spot-On Accurate! (Score 1)85

the encryption approach is the right one. It's fast, easy and much harder to circumvent.

If you are paranoid enough to encrypt the data locally after receipt at the phone, then you had better also examine the how the sender and the snapchat server deal with the data. Better setup a public-key system and figure out how to do the key management without discouraging Joe and Jane User.

## Comment Re:Title is Spot-On Accurate! (Score 1)85

Due to wear-leveling and the likes that is not good enough for data that is supposed to be gone forever.

You're presenting it as an all-or-nothing issue. There are a couple of shades of gray in between. The internal storage of Android devices is typically formatted as ext4, wtih the wear-leveling (I think) done by the flash memory controller. Accessing the "overwritten" data would require quite a bit more work than just analyzing a block-device image. I suspect that you might have to desolder the NAND memory modules.

And even if the file is deleted but not overwriten, I don't think it's that easy to find the right blocks in the correct sequence; compressed JPEG data past the header data looks pretty much like random data.

## Comment Re:I don't get it (Score 1)85

"I just can't think of a situation in which I would send a photo to someone and subsequently care whether they saved it or not. "

Sending nude pictures to your (teen) lover while reducing the risk that they get to be seen by the rest of the school if the relation goes sour. Or to prevent being charged for spreading child porn, like these kids: http://www.connectsafely.org/Commentaries-Staff/teens-convictions-for-child-porn-upheld.html

Maybe cheating husbands and wives who don't want to leave too many trails. Although I'd be rather suspicious if my significant other had Snapchat installed on her phone...

## Comment Re:CO2 at an active volcano? Who wudda thot? (Score 1)497

"cool the air to -78C and then collect the solid precipitate."

At that temperature, the vapor pressure is equal to atmospheric pressure. It would be like measuring the water content of air by cooling to just below 100 C.

You'd need to go quite a bit lower in temperature.
http://en.wikipedia.org/wiki/Carbon_dioxide_data

## Comment UDF file format (Score 3, Informative)309

any good reason not to use UDF for large flash cards?

I have no personal experience here, but this UDF compatibility matrix does not look too promising. Apparently there are five UDF versions and three variants within each version, and only the oldest versions (from 1996-1997) actually have wide OS support.

A bit more googling produces more comments from users about tricky incompatibilities.

## Comment Re:Nothing new (Score 3, Informative)202

"What remains: not much, really. Some glass, stone, metals. Not much that burns well."

I'm not sure what country you're describing, but here in the Netherlands, we separate paper, glass, plastic packaging (PE, PET, PP, PS), organic waste, electrical equipment, chemical waste. Stones (e.g. from breaking down a wall) are not supposed to be mixed with household waste. Laminated materials such as potato crisp bags and milk cartons, styrofoam, discarded household items go into the "other waste" bin. I'm not sure whether I'm supposed to, but plastic with food scraps sticking onto it don't make it to my plastics container since I don't want them to rot and smell. My trash bags will burn pretty well.

For the Netherlands, I think company offices are a big contributor to incinerable waste. They separate the paper, but not the plastics. Many company restaurants are not separating compostable waste from what the employees leave on their trays.

## Comment Re:"Cheap?" Who's still paying for chat apps? (Score 1)242

thousands of bucks per GB cost of an SMS

I see the upside of SMS'es costing the sender money: it throttles the rate of incoming messages. I fear the day that the spammers figure out how to use Whatsapp for massive spam runs.

Too bad that here in Netherlands the telcos are moving to unlimited-SMS plans due to competition with Whatsapp...

## Comment Re:Utterly irrelevant rubbish (Score 1)417

From this and your earlier post:

tell me you are not this dumb! ... ridiculous ... If you are not a complete retard ... nutcase born-again Christian ... morons ... mathematically retarded and should be removed

Rational arguments could be more convincing than strong language and ad-hominem attacks.

## Comment Re:Utterly irrelevant rubbish (Score 2)417

Motor vehicles are behind about 15% all CO2 emissions.

True on a world-wide scale. However, in the US, 32% of CO2 emissions is from transportation. It's harder to find numbers on motor vehicles in the US, but the closest I get within 3 minutes of Google is almost a quarter of annual US emissions of carbon dioxide (CO2). (...) The US transportation sector emits more CO2 than all but three other countries' emissions from all sources combined.

Unfortunately, it looks like there is no simple way to reduce CO2 emissions. Just saying "just cut all the CO2 sources except the my car, my airconditioning, and my incandescent bulbs" is a bit too easy.

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