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## Applying math to real world problems...

 Quote by uperkurk @OmCheeto, you say you calculated stuff like this when you were 12? Using the equation and notation I just saw in that PDF file? That stuff looks crazy difficult...
Going over my notes, it appears that I am incorrect. It appears that I placed the pennies a certain distance apart and calculated the time it would take gravity to bring them together in how long a time. The notes are not very good. I didn't include the original separation distance, nor the mass of the pennies.

 Quote by neo-Om's notes 8,650,000,000,000,000,000 years acceleration = 5.16e-38 cm/sec2 speed upon collision = ~1.41e-11 cm/sec

But I used to be able to do those calculations in my head, hence never wrote down the intermediate steps, and therefore have no clue now as how I calculated these numbers.

I have only the equations. And given that I was using a manual typewriter probably built in the 40's, I used all manner of substitutions for the greek symbols. I substituted a lower case "w" for omega, "@" for angular acceleration, etc, etc.

I do not recall ever taking a physics course in grades 1 through 12, so I assume I retrieved all the equations from our encyclopedia.

Here's a clue that perhaps I had intended to solve the orbital problem:

(please don't take note from the following. It appears I was putting together the jigsaw puzzle of physics, and made a few errors.)
 Quote by neo-Om's full set of unabridged notes orbit velocity = the square foot* of gravitational acceleration at the distance of r * the distance from the earths center. angular velocity = w(omega) v=rw w=radians per unit of time 1 radian = 57.3o impulse <> momentum momentum is a vector momentum is conversational(sic) (I think I meant conservational. Although perhaps not, as I probably didn't understand the concept at the time, and decided that they had made a typographical error. ) things do not really fall. the earth and the thing attract each other and meet at a point of zero. v=2*pi*r*w v=r*w v=r*w/57.3 t=f*r (then there were the numbers I mentioned earlier) 8,650,000,000,000,000,000 years acceleration = 5.16e-38 cm/sec2 speed upon collision = ~1.41e-11 cm/sec (then I continued) angular acceleration @ angular velocity w torque t linear acceleration a a = r@ f=mr@ t=(mr@)(r)=mr2@ I=mr22 = moment of inertia angular momentum = Iw w=fd w=mv2/2 work=mass*acc*dist
And that was it.

These notes were transcribed in the summer of 1977, along with 11 more pages of things I thought were important. I was about to enter the Navy, and was afraid my mother would throw everything out.

The problem of the orbit of the pennies did not re-enter my mind until yesterday. Thank you.

*I would not discover white-out until years later.

 Quote by OmCheeto Going over my notes, it appears that I am incorrect. It appears that I placed the pennies a certain distance apart and calculated the time it would take gravity to bring them together in how long a time. The notes are not very good. I didn't include the original separation distance, nor the mass of the pennies. Gads I was a nerd. But I used to be able to do those calculations in my head, hence never wrote down the intermediate steps, and therefore have no clue now as how I calculated these numbers. I have only the equations. And given that I was using a manual typewriter probably built in the 40's, I used all manner of substitutions for the greek symbols. I substituted a lower case "w" for omega, "@" for angular acceleration, etc, etc. I do not recall ever taking a physics course in grades 1 through 12, so I assume I retrieved all the equations from our encyclopedia. Here's a clue that perhaps I had intended to solve the orbital problem: (please don't take note from the following. It appears I was putting together the jigsaw puzzle of physics, and made a few errors.) And that was it. These notes were transcribed in the summer of 1977, along with 11 more pages of things I thought were important. I was about to enter the Navy, and was afraid my mother would throw everything out. The problem of the orbit of the pennies did not re-enter my mind until yesterday. Thank you. *I would not discover white-out until years later.
You must literally be a genius... At 12 years old I was playing video games and failing my times tables lol....

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 Quote by uperkurk You must literally be a genius... At 12 years old I was playing video games and failing my times tables lol....
The only purchasable video game available when I was growing up was called "Pong".

Or more specifically Odyssey, by Magnavox.

My oldest brother bought one. Mastered it in 12 seconds.

Boop! ....... Boop! ....... Boop!

And as for times tables, did you not see my comment on how I was an uber-nerd?

I sat down, during the summer, after I was told that there was more than one number base, and wrote out the multiplication tables, for all bases between 2 and 16.

This was long before computers were available, and a bit of a while before I would realize that knowing binary and recognizing hexadecimal would become important tools in dealing with these demon machines, with which I. hmmm... Computers are awesome.

When I got my last job, I discovered that the oldsters were using computers as if they were typewriters with TV screens. ie., They had not a clue of the inherent power of microprocessors and well written software.

I went on to write several pieces of software for that job. I'm pretty sure it eliminated at least 3 positions over the years.

As I've said before; "I somehow feel responsible for a bit of the unemployment problem."

Or something like that.

-------------------------------
ps. I was a genius. Mostly due to long hours of mind pleasing mental massage. It was the only thing to do as a child during our long cold rainy PNW months. Now I just sit and surf in a Lay-Z-Boy recliner, and burp once in awhile. So no, I am not a patent clerk.
 uperkurk: you're being trolled so hard :P Notice the best humor 2012 PF award.

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 Quote by tahayassen uperkurk: you're being trolled so hard :P Notice the best humor 2012 PF award.
and the confusion sets in....

Strawman!

Opps. Made an oopsie. I thought you were joking when you wrote "Though I do recall that when I was about 14, I converted a 4 function calculator into a stopwatch. I wish I knew half as much now as when I was young." Trolling is the art of deceiving someone.

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 Quote by tahayassen Trolling is the art of deceiving someone.
Deception is the art of deceiving someone! Trolling is something else entirely!
From wiki:

In Internet slang, a troll (pron.: /ˈtroʊl/, /ˈtrɒl/) is someone who posts inflammatory,[1] extraneous, or off-topic messages in an online community, such as a forum, chat room, or blog, with the primary intent of provoking readers into an emotional response[2] or of otherwise disrupting normal on-topic discussion

Trolls can use deception however. It is one of several tools.

 Quote by Drakkith Deception is the art of deceiving someone! Trolling is something else entirely! From wiki: In Internet slang, a troll (pron.: /ˈtroʊl/, /ˈtrɒl/) is someone who posts inflammatory,[1] extraneous, or off-topic messages in an online community, such as a forum, chat room, or blog, with the primary intent of provoking readers into an emotional response[2] or of otherwise disrupting normal on-topic discussion Trolls can use deception however. It is one of several tools.
It seems you know quite a bit about trolling. Perhaps too much...'

Not drawing any conclusions or anything...
you undercover troll!

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 Quote by tahayassen It seems you know quite a bit about trolling. Perhaps too much...' Not drawing any conclusions or anything... you undercover troll!
 :( the worst thing about talking to people about a topic you have no clue about is you have no idea when you're being trolled :(

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 Quote by uperkurk This is what I mean though... how is it possible to INVENT equations that can predict the orbit of planets?! It just seems impossible without actually being able to take a tape measure to it...
1) The equations were to describe motion in general.

2) If the laws of motion were true, they should apply to celestial objects, as well as everyday objects.

2) Using observations already made by astronomers, Newton could see if his equations matched real observations. In other words, by plugging observation #1 into his equations, did the results of his equation match observation #2.

In other words, he predicted nothing (at least originally).

3) And, actually, a tape measure would have come in handy. While Newton (and Keppler) could tell you Jupiter has to be x times further from the Sun than the Earth, he had no way of telling you what either of distances (Earth's or Jupiter's) were in kilometers. (This is why "astronomical unit" is historically such a popular unit of measure.)

And perhaps a great deal of his success was as much a result of DesCartes as Galileo and Keppler. It's no coincidence that two separate men 'invented' calculus within 10 years of each other shortly after DesCarte's Cartesian coordinates, etc, created the need to calculate the 'slope' of a curved graph.

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 Quote by tahayassen That was in his letter to Robert Hooke in February 1676. By giants, he is referring to Galileo and Kepler.
As a side note, Hooke was a very short man. This comment is also a direct put down of Hooke, who was no giant.

This according to John Gribbin.

On Topic.
It is easy to observe changes in motion. That is why Newton developed Differential calculus, to analyze the changes in motion of the planets. To create a mathematical model you start by expressing the problem in terms of differentials, once you have a differential equation for your system you can then solve it to arrive at simple time dependent equations of motion.
 Recognitions: Gold Member And he did it at 26, just because of boredom during sequestration from the plague rampant in the cities. And to piss off Leibniz. I find myself doing most calculus in physics on my graph lined notebook. Only use the computer to do tough graphs and watch Lenny do incredible physics whilst munching chocolate chip cookies. My hero.

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 Quote by uperkurk :( the worst thing about talking to people about a topic you have no clue about is you have no idea when you're being trolled :(
We will let you know when we start trolling you.

As to your spinning penny, I have no interest in solving the problem, as I see little "real world" use of the answer. (How long will it take a 300 kg generator to spin down with a coefficient of friction x, radius y, length z, once motive power is removed with no load? My answer: Who cares)

You might go to the physics or homework section and request guidance on how to solve the problem. Off the top of my head, you will need to know the following:

Mass of the penny
Initial angular velocity
(Some basic knowledge of Rotational Dynamics: Halliday & Resnick, 2nd Edition, Revised Printing, 1986, page 198)

From here you would measure the amount of time it takes for the penny to stop spinning.
This would yield, mathematically, a deceleration rate.
From that, I believe you could determine the coefficient of kinetic friction between the penny and your surface.

Then, with some mathematical knowledge of physics, you could extrapolate an equation which relates time, angular velocity, mass, etc.

Actually, I wouldn't solve the problem for you even if I found it to be a useful bit of knowledge. It's not allowed here.

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