Another Silly puzzle

Nish Nishant

Chris Losinger wrote:

do you know how airplane wings work?

That works on the vacuum principle too, eh? Regards, Nish

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Russell Morris

The series for e^x is more complicated than that: e^x = 1 + x + x^2/2! + x^3/3! + ... + x^n/n! + ... where n is an integer and goes from 0 to infinity If you differentiate term n of this series, you find that you get term n-1 as a result. That's why the derivative of e^x is still e^x :) I always liked that for some reason.

Richard Andrew x64

The sum will never even reach the number 1, much less exceed 100. And the candle gets extinguished from the carbon dioxide in our breath. Rich ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸

Chris Losinger

Nishant Sivakumar wrote:

That works on the vacuum principle too, eh?

a wing will create small pockets of (partial) vacuum as air moves around it. it's under debate as to whether this is the actual source of lift or not. Cleek | Image Toolkits | Thumbnail maker

Raj Lal

You got it right. Here is your prize Up [^] --- My Unedited article^

Wjousts

Funny, 'cos I'm up to 34000000000 or so and I've got a total of nearly 24 which is clearly more than 1. Look at the sequence more carefully. It's not 1/2 + 1/4 + 1/8 +....

Nish Nishant

Troposphere wrote:

The sum will never even reach the number 1, much less exceed 100.

You are kidding, right? :omg: It crosses 1 after the 3rd fraction in the series. 1/2 + 1/3 + 1/4 = 1.08333 Regards, Nish

Nish’s thoughts on MFC, C++/CLI and .NET (my blog)
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Wjousts

Woohoo! Now that's a big candle. Need a lot of puff to blow that one out. That's what she said ;)

Raj Lal

Troposphere wrote:

And the candle gets extinguished from the carbon dioxide in our breath.

And if you blow air by some other method it won't ? --- My Unedited article^

Dan Neely

I want to say this is a nonconverging series, but it's been a long time since I did those in math, and google ignores /'s even when they're inside of quotes.

Raj Lal

OK lets divide it in two parts Question 1

Quartz... wrote:

When will the sum of this series exceed 100 ?

Question 2

Quartz... wrote:

Will it EVER ?

simple looking problems, are sometimes the most challenging ones. --- My Unedited article^

Jerry Hammond

I usually clean the wax out of my ears for that effect... Asking someone to define CP is like asking someone to define art. It is a known, a tangable thing, a state of being. To define it is to limit and miss its true nature.

Chris Losinger

it's very close to the Harmonic Series[^], it just starts with i=2, instead of i=1. Cleek | Image Toolkits | Thumbnail maker

Raj Lal

Mathworld here[^] --- My Unedited article^

Marc Clifton

Chris Losinger wrote:

it's under debate as to whether this is the actual source of lift or not.

You mean they still don't know? I've always been told that's why the plane lifts (but honestly, I never quite believed it. Just stick your hand out a moving car window and it seems that the angle of attack has a major affect as well, though maybe that's BECAUSE of the low pressure on the back of one's hand). Marc Pensieve Some people believe what the bible says. Literally. At least [with Wikipedia] you have the chance to correct the wiki -- Jörgen Sigvardsson

Nish Nishant

Marc Clifton wrote:

You mean they still don't know?

Explains those bumpy rides, and if you are flying Air Canada or a domestic Indian airline, the bumpy part of the ride is seriously stressed upon! Regards, Nish

Nish’s thoughts on MFC, C++/CLI and .NET (my blog)
The Ultimate Grid - The #1 MFC grid out there!

Wjousts

Quartz... wrote:

Question 1 Quartz... wrote: When will the sum of this series exceed 100 ?

Don't know. Some very large number, I'm up to around 58000000000 and it's only at about 24.36 doing this by brute force. I'm sure this is some known sequence and there is some very clever and simple way to calculate it, but I'm not up to the challenge.

Quartz... wrote:

Question 2 Quartz... wrote: Will it EVER ?

I'm pretty sure it has to eventually. The number keeps growing but by progressively smaller steps, but it still keeps growing. Shouldn't you ask question 2 first?

Chris Losinger

Marc Clifton wrote:

You mean they still don't know?

this site[^] explains it pretty well, i think. but it's not the traditioinal Bernoulli's explanation (high pressure below, low pressure above). this one explains it as: The lift of a wing is proportional to the amount of air diverted down times the downward velocity of that air. so, some might know, but the rest of the world disagrees. Cleek | Image Toolkits | Thumbnail maker

Russell Morris

Jon Sagara wrote:

e100?

Wait - after working this a bit, I'm getting that e100 is a good approximation of the number of terms it would take for the sum of that series to get up to 100. Is that what you were indicating? If so, I apologize for my first 'correction' :-O From my musings, the above series is the Harmonic Series, but starting at k=2 (Chris Losinger has noted this already, it appears). In addition, ln(n) is a good approximation of this series' value at n. Therefore solving: ln(n) = 100 for n would approximate the number of terms in the series needed to get the sum of the series to 100. Solving this equation, I get: n = e100 which is what you originally wrote. Did you come to this conclusion in the same way I did? I hope I'm not making myself look silly - I'm 6 years away from my last math class. It's amazing how the details become so fuzzy after such a short time...

Andy Brummer

Chris Losinger wrote:

a wing will create small pockets of (partial) vacuum as air moves around it. it's under debate as to whether this is the actual source of lift or not.

Do you have a source for that? I can't think of anything else that would generate lift.

I can imagine the sinking feeling one would have after ordering my book, only to find a laughably ridiculous theory with demented logic once the book arrives - Mark McCutcheon