Recent content by PeteSF
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What Are These Abbreviations For Familiar Quantities?
8 Tones in an Octave! (Not the best answer, though.)- PeteSF
- Post #25
- Forum: General Discussion
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What Are These Abbreviations For Familiar Quantities?
Remaining solutions in Last Group: 26) 9 LIves of a Cat 23) 23 Pairs of Chromosomes in the Human Body 31) 6 Balls to an Over in Cricket[/color]- PeteSF
- Post #24
- Forum: General Discussion
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High School Is the beam from these Class IIIB lasers truly visible without any added medium?
Not that I doubt you :wink:, but would you have any supporting references? -
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Undergrad Collision Damage Comparison: 40mph Head-On vs. 80mph vs. Rest
A 40mph-40mph head-on collision does the same damage as a 40mph collision with an immovable object. An 80mph collision with an object at rest of equal mass and strength object not attached to the ground (eg a car oil an oil slick) would also do the same damage. If the car at rest is in... -
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Graduate STR, one-way speed of light and conventionality
Sure we can. All you need is some kind of synchronization at different places. Radio telescope arrays and Very-Long-Baseline-Interferometry relies directly on the one-way speed of light. For that matter, the standard two-slit interference pattern relies directly on the one-way speed of...- PeteSF
- Post #2
- Forum: Special and General Relativity
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High School Is the beam from these Class IIIB lasers truly visible without any added medium?
I suspect that the pictures could be real, but taken with a lengthy exposure (perhaps several seconds). According to Wikipedia, high intensity lasers can be visible in clean air by Raman scattering or Rayleigh scattering. WiseGeek.com also suggests that green-beam lasers are visible in... -
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Physics Project (Egg Drop, again)
Note that high viscosity doesn't necessarily mean high density. Oil, for example, is more viscous and less dense than H2O.- PeteSF
- Post #24
- Forum: General Engineering
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Ask a Stupid Quetion Get a Stupid Answer
We're already doing it - this thread is case study in BA (biological intelligence), and why it isn't. If I say "mouses", "gooses", "sheeps", "persons", "octopods", and "radiuses", instead of "mice", "geese", "sheep", "people", "octopodes", and "radii", why do grammarians get their knickers in...- PeteSF
- Post #2,266
- Forum: Fun, Photos and Games
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Physics Project (Egg Drop, again)
Fantastic! How's the landing accuracy? Can you nail a 40cmx40cm square?- PeteSF
- Post #18
- Forum: General Engineering
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Calculate Initial Angular Speed of Fan | High to Low Button Pushed
--> Homework forum??- PeteSF
- Post #2
- Forum: Introductory Physics Homework Help
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High School What Is Pluto? Can We Live There?
Well, the article also says (correctly) that the atmosphere freezes regularly. What it fails to clarify is that if Pluto and Charon do share an atmosphere, then it would only be shared when the atmosphere is not frozen.- PeteSF
- Post #9
- Forum: Astronomy and Astrophysics
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High School Solving Geometry Problem with 3 Equilateral Triangles
It's more likely that I've got mistakes in there (you picked one up already - angle b is indeed CHJ, as on the diagram). Yes, the idea was to add all the bits of the AC segment. See if you can go through and add them all yourself, without worrying about how I tried to do it. Start by drawing...- PeteSF
- Post #11
- Forum: General Math
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Graduate Why Do Gyroscopes *Start* Precessing?
The original question mentioned a gyroscope with axis parallel to the ground - at 90° to the gravity field. -
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High School Solving Geometry Problem with 3 Equilateral Triangles
After a touch more work, it looks like you need basic calculus to find the minimum in that equation... Have you done derivatives using the quotient rule?- PeteSF
- Post #9
- Forum: General Math
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High School Solving Geometry Problem with 3 Equilateral Triangles
Consider the attached diagram (which I made too small. Sorry!) H is the midpoint of CE I is the center of the circle (where the perpendicular bisector of CE meets AB). J is where a perpendicular dropped from H meets CF. Now: AC = 28cm = HJ.tan(b) + HJ/tan(b) + x.tan(b) + x.tan(60°)...- PeteSF
- Post #8
- Forum: General Math