Saturday, October 27, 2007

Fly Gundam!


I was watching an episode of 0080: war in the pocket. I noticed the space colonies were rotating. The different sections had different rotational speeds.

With further research I found out that many of these colonies are called O'Neill cylinders. One the first designs was "island one" a sphere with a diameter of 1.609km (804.5m). So to find the velocity at which the colony would have to rotate is using F= m(vsquared/r) to get 88.8 m/s. Another design calls for a cylinder rotating in different sections at different speeds. There is even an outer ring that rotates at various speeds for farming. In Gundam, the cylinders probably rotate way faster than 88.8 m/s since the rotation is too fast (for visual effect). Interestingly, in Rendezvous with Rama the object being explored also seems to be an O'Neill cylinder except without the mirrors and windows (needed for light).

These cylinders would need to be placed at Lagrange points. These points would allow a colony (only affected by gravity) to remain stationary between two objects, say the moon and earth. <> wikipedia includes some ways to calculate the five Lagrange points. This is demonstrative of center of mass, it being essential. However this is no longer a uniform circular movement since the objects take elliptical paths.

A large problem that confronts space exploration is the effect that radiation in space will have on colonists/explorers. At the scale of the O'Neill cylinder however, the air and the steel (perhaps another metal) hull will be sufficient protection.

Personally I can't wait for space colonies.. there's just something so enticing about space.

Sunday, October 21, 2007

Conservation of Momentum

Admittedly this video isn't that cool. By the way, I hope the other embedded video works now.



However, this is an example of (variation upon) newton's cradle. It's better than showing you the one on my desk. Here, momentum is conserved. When one ball is pulled back and allowed to hit the stationary balls the momentum is transfered to the ball on the opposite side and it moves. Here the balls (of same size and mass, and same plane of movement) are involved in an elastic collision. The KE is not changed to anything else. I also see this concept in the bowling ball return. When there is a line of bowling balls and a ball comes back and hits the series of balls only the last ball moves away. So anyways, happy rest of weekend everyone.

Sunday, October 14, 2007

Joon Lee!


The other day the car I was ridiing in got hit by another car. Although Hawaii state law is handy with its "no fault" clause it was obviously the other drivers fault. Turning onto a one lane street and signalling, the other driver (Joon Lee) sped up to pass and crashed into the front right of the car.

Now the car door hardly opens, however, I feel pity for the other car which seemed to sustain even more cosmetic damage. Fortunately nobody was hurt although my neck felt a little stiff.
I feel what helped reduce the effects of the minor collision were the "crumple zones" on the car. Although the impulse of the collision is the same, it increased the duration it took the other car to have the collision and thus reduced the average force. Thank goodness for that. Happy rest of weekend everyone!

Sunday, October 7, 2007

Rube Goldberg FTW!

I'll have to say that Rube Goldberg contraptions are awesome.

In what is basically an interactive physics program, Garry's Mod, one can simulate different physics (gravity, even static and kinetic friction) but heck, to put it bluntly, nobody talks about Gmod in those terms very often. But! when you're messing around with Rube Goldberg contraptions very minute differences can make something go amiss.

So here's a video that I really like. Everywhere there are examples of physics. I like the part at the end where the crates slide down a massive ramp. The people at the end are encountered by a massive load of kinetic energy because satrting from higher up means more potential energy and we all know for conservation PE + KE = KE +PE, although I wonder if the creator had to reduce some friction on the ramp. Well anyways, this is some fun fun stuff (to me at least :p). The only limit is imagination! (ha what a hackneyed phrase)