Rowboat "on a Treadmill" Question
 

Say you are rowing a boat upstream as fast as you can. The water is flowing at 2 miles per hour, and your speed against the current is 4 miles per hour. Your rubber ducky blows off the boat, but you don’t notice. An hour later, you realize your ducky is gone. You turn around immediately and row back downstream as fast as you can. How long does it take for you to reach your ducky?

You don't reach the ducky ever because the rubber crocodile has eaten him

Roosevelt was visiting.
They hadn't fed the piranhas in days.

Bye-bye ducky, bye-bye.

upstream you are making 4mph against 2mph for 1 hour, so you've covered 4 miles (assuming the stream is really straight and you are measuring speed against a stationary reference, like land and not a changing reference like the water)
When you head downstream you are rowing at 6mph and the current is adding 2 mph for a total of 8mph. You would need to row for half an hour to return to the spot where your ducky fell off. An hour and a half has elapsed since the ducky fell and in that time the ducky has traveled, at 2mph, 3 more miles. You need to cover three miles to get to the ducky's current position. This will take you 22.5 minutes. in that time the ducky will have traveled another 3/4 of a mile. To close that gap and get within range you need to row for a few more minutes and use a full choke.

Somebody reads "Ask Marilyn".

How could you not notice the rubber ducky blowing off? He had curry for tea last night and the smell ... the smell ... and the air turned green, I mean a real vile shade of green.
Which way was the wind blowing?

I read Ask Marilyn today, too. ;)

Allowing a few simplifying assumptions...
no wind
uniform current
no eddies etc
The speed of the current is irrelevant since both boat and duck are in it. You've rowed away from Ducky for one hour, so to get back you must row towards him for one hour.

ur such a spoilsport

but he's got his ducks in a row

How far can a duck go, in a bathtub?

I thought I was the only one that read the Parade magazine in the newspaper. I mean, besides the Readers Digest large-type crowd.

I'm a little surprised you get the dead tree edition of the paper, Flint.

I thought I was the only one who did that. I just didn't get a chance to read the paper yesterday.

1.5 hours. You need to solve two equations. First: the distance the boat travels Db is 6 miles + the distance the duct travels Dd since the ducky has traveled 2 miles in an hour while the boat has traveled 4 miles in the opposite direction.
The second equation is the time of travel from the time the loss of the ducky was detected is the same for both. Since time = distance/speed, Dd/2 = Db/6. Note the boat speed downstream is 4+2 = 6 mph. Solving both equation will give the time of 1.5 hr during which the ducky has traveled 3 miles and the boat woild travel 1.5 hr x 6 mph = 9 miles (6+3).

Your first post is to do math everyone hated in elementary school. Welcome, Lilliput1. You're obviously our kind of people.

And you're all wrong. First off, the ducky keeps moving while you're chasing it, and it probably wasn't water tight to begin with, and you're never going to find that particular rubber needle in a wet haystack anyway ... I'm going with two or three days, because it's going to take that long for me to get back to the car, go home, recover from the strenuous activity, and finally get around to going out to the store to buy a new ducky as there is absolutely no way I'm putting a duck that's been in a nasty, cryptosporidium contaminated stream back in my bathtub.

Sometimes you just have to replace the duck. It's the only logical answer.

Thanks Wolf! Math problems I understand! People I find hard to!

I'm seriously researching some type of e-reader device right now. I constantly have a "to-read" stack of printed pdf articles on my nightstand, it's ridiculous. But I really do not like reading long texts from a glaring LCD monitor.

can pdfs be loaded onto kindle-type things? My pal has a kindle and it is a lot easier on the eyes than an LCD but until someone makes a firmware hack for them so I can use my device without being treated like a criminal, I'll stick with paper.

I just read up on it and I guess one can do this.

android is your friend.

the android marketplace has kabillions of apps, including the ability to read pdfs.

find a display you like, find the source of your likely reading material (prolly the internet, maybe the libarry, maybe amazon) and then find the device that lets you get (or get to) the info you will want to read.

Ideally, I think a tablet (computer, or not) is the tool of choice. find one you like, and then start.

Nah, I don't want a phone-like thingy with a bazillion apps. I don't want to basically carry my computer with me. I'd like to have a way to read PDFs without having to look at an back-lit illuminated screen or print them out.

Sort of like an Ipod, but for reading books, PDFs, Word docs, and XLS files.

What about one of those fancy real-world projector thingies.

Or just put the pdf through a data projector, onto your bedroom ceiling, and read away until you doze off...

I suggest instead that you hire someone to follow you around and read the PDFs to you.

What's your availability?

How much do you got?

For this voice, you'd better be prepared to shell out, baby. (Actually, that's not true. I'm not unionized, and I undercharge in general because the kind of clients I attract are also the kind that are liable to decide that they ought to save money by having some employee do it at their desk on an MMO headset mic.)

I would seriously make it worth your while. In a while.
[/gladly pay you Tuesday for a hamburger today]

Made me think of this:

You mean like the 10 commandments?

no, like an aspirin

I saw that Android has a CrashPlan client--you can pull down files from the cloud (the same files that are automatically backed up from your PC).

So I'm thinking, a Nook running Android (I want a good reader-quality screen) but then I gather that the "Android" Nook doesn't let you access the Android market. I guess this is why people root them to an SD card, but . . . haven't they released a Nook that natively runs on REAL Android? I thought they did.

I'm so confused.

Now Kindle released the "Fire" which is specifically designed to be a cloud device. But apparently on Amazon's own clouds they've been developing.

When I look up the Wikipedia article "comparison of e-book formats" I see that Apple devices and Android devices are tied for most kinds of file compatability, but the Nook sucks at this.

DOES THE GODDAMN ANDROID NOOK RUN ANDROID OR NOT???

Only if you hack it.

Let me say it for you slowly ...

K.I.N.D.L.E.

And a copy of Calibre.

PDFs can be read on the Kindle, but for straight reading, you really want to run them through the converter ... you can zoom and navigate around the page of an unconverted PDF, but it's a pain in the ass ... of course you can get a Kindle DX, which gives you a full page size. I have read unconverted PDFs on it, but tend to prefer the conversion so I can change the font sizes to my liking.

Yes,

the hack is easy, free, reversible. what more do you want?

I guess I want the market to decide what "the" format is, e.g. VHS vs. Beta. I'm not an early adopter--I have no interest in blowing money on a device that only meets half my needs, and then fades into obsolescence in a year or so. I never do that, ever.

This market might not be ready for someone who makes careful purchase decisions to get involved at this point.

Sometimes the market never reaches that point. I've been waiting for a box that will play bluray discs, DVR broadcasted shows in high def, and also stream Netflix.

The technology is there, and has been for a couple years, but the licensing hurdles are too big. So it will never happen. I'd have to build it myself out of a PC and install special software etc.

Sometimes you just have to buy an imperfect product, or go without.

I think the reason I'm not going 100% with an Android-rooted Nook is that the Kindle 3G comes with free wireless, forever. With the Nook, I'm not sure if I'd have to pay for connectivity. I guess as long as I can get on my home wireless router I don't really need 3G.

Incidentally there was a whole thread intended to be about this. I got kind of scatterbrained.

Nine equations True Geeks Should (at Least Pretend to) Know
Wired
by Brandon Keim
Nov 4, 2011

This is very much for geeks, but maybe an interesting read none-the-less

I'm a little embarrassed to say I am zero for nine, and I'm not pretending.
.

0-fer. I did recognize some of the variables, including S above. A math geek I am not, by their standard.

8 I recognise and understand. It is the simplest one.
1 I recognise and almost understand, and appreciate.
4 I recognise but don't understand and couldn't do a thing with.
2 and 5 I've heard of.
The rest are new to me.