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## Writing Resources from Fifteen Minutes of Fiction

The following is a piece of writing submitted by Douglas on December 15, 2009
"I wrote this at 5:00 AM, before finishing my first cup of coffee, so if I made mistakes in my math or physics, please be forgiving. :)"

## The Physics of Santa's Journey

Dear Santa,

The world population is now over six billion people. That's a lot of people. If we figure that the average family size is four people, and that of those families, only 75% of them have people who are good enough to get presents from you, that means you have to visit about 1.1 billion homes on Christmas Eve.

Normally we think of a "night" as being about 8 hours, but of course, if you time things properly, you have much more time to do your rounds; when it's 6:00 AM in India, it's early evening in Maine. So say you've got 24 hours to do your visits to those 1.1 billion homes.

That means you need to visit about thirteen thousand homes every second, or forty-seven million visits every hour. Let's be generous and assume that (on average) the journey from one home to the next is one tenth of a mile.

From this we conclude that you need an average speed of 4.7 million miles per hour. Now, that's not the part that really interests me; others have done those calculations (though at the time they were done the world's population was significantly less, and you could comfortably travel at about a third the speed now required).

What interests me is this: in order to maximize your efficiency, and make this whole thing possible, I think you must constantly accelerate through half of each journey, then constantly decelerate through the second half of each journey.

Using my good ol' Physics equations,

d = vit + 1/2at2

.05 miles = 1/2a(1x10-18 sec2)

The resulting acceleration has too many zeroes for me to count, but it looks like it might be in the quadrillions of miles per second per second.

And if we assume you and your sleigh (with all those presents!) have a combined mass of 1,000 slugs (a very generous estimate, considering how many gifts you are lugging around) then the amount of force being applied to you, your sleigh, your reindeer and the gifts is in the...hmmm...what do we call that? Quintillions?

My point is this: even if you and your reindeer can magically withstand those kinds of forces, I'm pretty sure my new Van de Graff generator will not.

Please use UPS or the USPS this year.

With kind regards,
A Concerned Physics Teacher

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