Austin Matzko's Blog » McDonald’s http://austinmatzko.com A blog about philosophy, Christianity, web development and whatever else I feel like writing about. Wed, 16 Mar 2011 17:14:59 +0000 en hourly 1 http://wordpress.org/?v=3.2-RC4-18391 McDonald’s Spaced Out http://austinmatzko.com/2008/04/16/mcdonalds-and-astrophysics/ http://austinmatzko.com/2008/04/16/mcdonalds-and-astrophysics/#comments Wed, 16 Apr 2008 16:31:42 +0000 filosofo http://www.ilfilosofo.com/?p=445 This is McDonald’s idea of making their Happy Meals educational. (That I took this photograph may also be proof of bad parenting on our part, but let’s overlook that.)

You can jump 6 times higher in space!

I think what they mean is that you can jump six times as high on the Moon.

In case you were wondering, that’s because the surface gravity of the Moon is 1/6 that of the Earth’s. It’s not because the moon has 1/6 the mass or the diameter of the Earth, as you might suspect. In fact, as you can see here, the mass of the Moon is 1.23% of the Earth’s, and its radius is 27.25%.

Surface gravity can be expressed like so:

( Surface gravity of the Moon/Surface gravity of the Earth ) = ( Mass of Moon/Mass of the Earth ) / ( Radius of Moon / Radius of Earth ) 2

Plug in the numbers, and you get the following:

( Surface gravity of the Moon/Surface gravity of the Earth ) = ( 0.07349 x 1024 kg/5.9736 x 1024 kg ) / ( 1738.1 km / 6378.1 km ) 2

Which ends up as Surface gravity of the Moon/Surface gravity of the Earth = 0.1656 ~ 1/6

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