Always expect a train

[kinzel]

So, anyone got a lucky rabbit's foot you need to energize?

Ask this guy ...

http://www.startribune.com/local/27991064.html?elr=KArksLckD8EQDUoaEyqyP4O:DW3ckUiD3aPc:_Yyc:aULPQL7PQLanchO7DiUI

Or maybe ...this lady ...
http://seattlepi.nwsource.com/local/378213_oregontrain09.html

The moral of the story: most folks ain't got this luck.

Comments

Math-scream

[katarinaf.livejournal.com]

I know several other people have done an excellent job with this, but since I asked my son, the math major, for help I wanted to send it in to you. Hope it helps.
The acceleration created from maintaining an object in a circular path, known as centripetal acceleration, can be calculated using the equation a = (v^2)/r where a is the magnitude of the acceleration, v is the magnitude of the velocity, and r is the radius. Solving for the velocity yields the equation v = sqrt(a*r). The radius of the drum is given to be 3 meters (half the diameter of 6 meters) and we can substitute any fractional multiple of g (9.8 meters per second-squared, the acceleration due to Earth's gravity) for a to determine the necessary velocity. So, if you wanted the drum to create an artificial gravity equivalent to 1/2 g, simply substitute that for a in the above equation and you get v = sqrt(.5 * 9.8 * 3) = sqrt(14.7) = 3.834 meters per second. If you want to know what that translates to in terms of rotational speed, divide the velocity by the circumference of the drum (circumference = 2 * pi * r = 2 * 3.1416 * 3 = 18.85 meters) and you get 3.834 / 18.85 = .2034 rotations per second (rps) which is equivalent to 60 * .2034 = 12.2 rotations per minute (rpm).

However, this is all only valid for the part of the person that is physically touching the rim of the drum. If the person is standing up inside the drum, then only their feet would be experiencing an acceleration of 1/2 g, whereas the rest of the body would be experiencing less and less acceleration the further from the rim (and the closer to the center) it was. So a 1.85 meter (approximately 6ft) tall person standing upright inside a 6 meter wide drum rotating at .2034 rps would be experiencing 1/2 g at their feet but approximately 1/5 g at their head. If, however, the person were laying flat against the inner wall of the drum then the acceleration they experienced would be essentially uniform at 1/2 g. The reason we experience a uniform gravitational acceleration on Earth is that the distance between our head and our feet (1.85 meters in this example) compared to the radius of the Earth (approximately 6400 kilometers) is essentially insignificant (less than one one-thousandth of a percent), whereas in the drum example it is 61.6%. Hence you'll want to get a much bigger drum (or a much smaller person) if your aim is uniform acceleration, unless you want people to slide on their backs when moving through the drum.

I hope that clears things up.