a thoughtful web.
Good ideas and conversation. No ads, no tracking.   Login or Take a Tour!
comment by kleinbl00
kleinbl00  ·  1537 days ago  ·  link  ·    ·  parent  ·  post: Inside SpinLaunch, the Space Industry’s Best Kept Secret

You know, just for fun.

Moment of inertia is

(mass1)(mass2)/(mass1 plus mass2)(distance)^2 is (1600)(1600)/3200 times (37m)^2 is 1.1e6 kg m^2 (presuming our 120 feet of kevlar has no mass).

kinetic energy is 1/2 I omega^2 is (0.5)(1.1e6)(74 rad/sec)^2 is 3.01 gigajoules.

Presume it's perfect. Presume it's frictionless. Presume sunshine and rainbows. You just pumped 833 kW/h into this thing and you're letting it go in a millisecond. That's 1400lbs of TNT, which is troublesome, because the linear energy is 1200lbs of TNT, which means ThurberMingus' entirely-expected flat spin has some real power behind it.





Devac  ·  1536 days ago  ·  link  ·  

    Presume it's perfect. Presume it's frictionless. Presume sunshine and rainbows.

Sounds like a motto on Wile E Coyote's wing at ACME university.

kleinbl00  ·  1536 days ago  ·  link  ·  

What this project needs is a high school physics teacher with a sense of humor and duty who walks his class through all the stuff they can see as a problem and then makes them do it on a chalkboard for Youtube.

Now'd be about the time. In the US, the first semester of high school physics is all Newton. Second semester becomes E&M. In between you do a little rotational stuff. It's pretty much the season to remind the class of everything they've learned so far and let them get investigative on it.

I would love to see a bunch of 11th graders schooling Kleiner Perkins on Newton's Laws. You don't even need to get into the more advanced shit ("If a 60cm^2 stalk of pure aramid fiber is necessary to support the centrifugal load of the launch vehicle, what will you make the release mechanism out of?"), just let 'em show off what they learned before Christmas.

Devac  ·  1536 days ago  ·  link  ·  

I sent an email to some of the teachers I met through my outreach series with old uni. Now it's a waiting game, but if I were to bet, the most difficult part would be getting OKd for recording.

Syllabus-wise, I think we're going Newton, thermo, E&M, mechanical waves and the senior year was optics + modern physics. Dunno if it's still the case, our board of education likes to look busy.