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Old 11-27-2009, 09:04 AM   #30
Basia Halliop
Join Date: Jun 2006
Posts: 711
Re: YouTube: Push Test to Nikkyo

"If you'll note in the vid, when my partner suddenly takes his arm away, I don't move into him. So, I'm not exerting a force back into uke. So, if I'm not equalizing the force that uke is projecting, then something else must be going on, right?"

No, not really. If I put a book on a table, gravity exerts a force downwards on the table equal to F = -mg where m is the mass of the book. The table exerts an equal and opposite force called the normal force, this is why the book doesn't go through the table. Likewise, the force the table exerts on the floor is now increased by m, and the normal force exerted by the floor on the table is also increased by m. Yet, the table does not move upwards when the book is removed, since the normal force exists only when something is pressing the table. It doesn't continue afterwards.

Actually, stealth radar works precisely _because of_ basic physics . Some of it is cancellation of one electric field with another equal and opposite one, much of it is altering the angles of reflection to minimize how much goes back to the sender, some is using materials with different dielectric constants. All very fundamental and measurable (and believe me, they measure it to death) physical stuff... It's the same basic problem as antireflective coatings on eyeglasses, just a more complex system so more factors to the solution.

But that's way besides the point, I suppose. I take your point about vocabulary... it's not really the point of your discussion, I presume. I imagine it's easier to show what you're doing than to explain how it actually works, without shared language.
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