# Search results

Pit vipers, for example the rattlesnake. The pits are cavities with a heat sensitive lining. Works like a pinhole camera of sorts. The resolution isn't very good but they do seem to be able to direct a strike at warm blooded prey. I don't think any of the constrictors have pits.
2. ### Force exerted by moving air?

Obviously yes, but from the way your question is worded you are looking for a simple formula. There is none. The force air exerts on an object is extremely dependant on the way air flows around it. That means the shape of the object is very important. If you're really interested, find some good...
3. ### Field Constants

I don't know. I was explaining a minor point of _Newtonian_gravitation_ and found myself dodging black holes, parahelion precession and gravitational radiation. Geez. :biggrin: Sorry if I offended anyone. I hope in all this mess the op found a satisfactory answer to his original question(s).
4. ### DREAD weapon system, power requirements

Dimpling actually reduces drag. That's why they do it to golf balls. (Which is what I still say is what the picture is.) They induce a small amount of turbulance, which while on it own would increase drag, has the overall effect of altering the stream flow into a more efficient pattern. Tests...
5. ### DREAD weapon system, power requirements

Kind of gives a whole new perspective to the term "fail deadly" , doesn't it?
6. ### Field Constants

I think you misundersood me. The question was asked why gravitation uses a composite G variable while em uses 1/(4*pi*e0). I essentially answered that it was convenient for em to do so while in gravitation it isn't particularly helpfull as you just demonstrated. In em e0 is used for relating a...
7. ### Field Constants

Sorry, I should have been more clear. The point I was trying to get across was in Newtonian physics there is no particular incentive to write it in the form 1/(4*pi*g0), so the original poster won't find a g0 in any textbook he is likely to be studying. Gauss's law is inherent in the form of the...
8. ### Field Constants

I almost mentioned general relativity, but I didn't want to confuse the issue. In em the form of Maxwell's equations makes e0 useful. There is no incentive for g0, in fact I've never seen it outside of some tinkering I did when I first asked the same question you did.
9. ### Field Constants

Gravity's 1/(4*pi) *g0 =G , it's embedded in the gravitational constant. Gravitation flux doesn't have anything similar to em induction (relating a changing E field to an B field and vice versa as in Maxwells equations) so it isn't particularly useful to write it out that way.
10. ### To verify the estimated mass of a neutron

There is a large disparity in mass between the Au nucleus on the one hand and the alpha particle and neutron on the other. A case of a marble wacking into a stationary bowling (sticking?) and knocking out a pea sized peice of the bowling ball. So couldn't it be approximated by the momentum of...
11. ### Field Constants

It's really just a scaling factor, needed because of the arbitary nature of systems of units. It relates the E field intensity units to the unit of force and the unit of charge. The numeric value depends on the system of units chosen. (MKS, ft-lb-slug, etc.) >>edit I should clarify what I...
12. ### Bubble Chamber

Glad to help. By the way, did you ever hear the story of how the bubble chamber was invented. Particle physists had run into a problem in that cloud chambers weren't accumlating enough collision events (a particle actually striking a nucleus) due to the high energies of the particles and the low...
13. ### Bubble Chamber

Depends on what you mean by ionizing powers. If they have equal energy then yes they will create roughly the same total number of ions as each slows to a stop. But a neutron takes longer to slow than a proton, no charge to strip electrons from atoms near its path. A neutron does have a magnetic...
14. ### Bubble Chamber

I see what you mean. Iirc, most (perhaps all) neutral particles don't leave an ionization trail strong enough to trigger a bubble trail. They don't interact with the liquid strongly enough.
15. ### DREAD weapon system, power requirements

I think I see what your getting at. A washing machine acheives a dynamic balence by allowing the "rotor" axis to move in a small circle, as veiwed from on top. (Sighting straight down along the axis) This has also been used to stabilize the wheels on cars and on internal combustion engines and...
16. ### Easy question, magnetic poles

Magnetizing an iron rod with a permenent magnet works something like this. Throughout the structure of the iron (or steel and some alloys) are regions called domains. The entire rod is divided up into them. The spins of the electrons responsible for ferromagnetism tend to "cooperate" within a...
17. ### DREAD weapon system, power requirements

It's really beyond direct analysis. To many variables.. In a situation like this it would most likely need complex computer modeling. But you can predict generally that it must recoil, that unless you bolt it to a concrete bridge abutment you wind up torquing the plane of rotation of what is an...
18. ### Easy question, magnetic poles

All magnetism results from rotation or motion of charge. In a permanent magnet this is the alignment of the spin properties of the electrons in the material. For a bar magnet this can be visualized as a current circulating around the long axis of the bar. Now look down one end. The current is...
19. ### DREAD weapon system, power requirements

That just transfers the recoil to the vehicle. Which will rock back on it's chassis. Torquing the rotor axis. Which _is_ a gyro and will either come apart or precess violently, throwing the aimpoint all over creation. Everybody dive into a foxhole. :smile:
20. ### DREAD weapon system, power requirements

Most likely explode. Even if it didn't it would go into some pretty wild precessions. It would be impossible to control the aim. You can't even elevate the gun while the rotor is spun up. Ever play with a toy gyroscope?
21. ### Medium of light

tech by trade First let me be clear that dextercioby is absolutely correct. But I think that for clarity it would be good for you to understand that the distinction dex is making is of major importance only in the realm of Relativity. In other words where you would swich from using Newtonian...
22. ### DREAD weapon system, power requirements

It does mention that there is a sonic boom. But there wouldn't be a muzzle crack when a conventional firearm "uncorks" and vents the excess propellent gas. This is usually much louder that the bullet's sonic boom. What bother's me is the claim of no recoil. If the designer is that uninformed...
23. ### Physics confusion

#1 Conservation of Energy. Energy acquired from g*m*delta h = rotational + translational kinetic energy. #2 The "momentum of cannon and ball are equal" is a trick answer. The magnitudes are equal, yes. But momentum is a vector, and two vectors aren't equal unless both magnitude and...
24. ### Space Station Physics

So did I. Hmm... Here's a more direct solution. w=v/r rad/s af=w^2*r ah=w^2*(r-2) ah/af=.99=(r-2)/r af = 1.00*g =w^2*200 To be honest I'm not entirely sure why my first method worked. I think I subconsiously realized the limiting factor was r. Or maybe I was just lucky.
25. ### Physics confusion

The first answer is D because the center of mass of each shape dropped the same heighth, so each aquired the same amount of kinetic energy. Technically, the cannon and the ball don't have the same momentum. Momentum is a vector. But as long as you understand that the center of mass does...
26. ### Space Station Physics

When af (a at your feet) =1.00*g = v^2/r then ah = 0.99*g =v^2/(r-2) so ah/af = 0.99 =(v^2/(r-2)) / v^2/r
27. ### Potential divider

When you add Rl in parallel with Rb, the current through Rt increases, and It = Ib+Il (the currents through Rt, Rb and Rl respectively) Also, Vt = It * Rt , Vb = Ib*Rb , and Vl =Il*Rl (Vt,Vb,Vl voltage across Rt,Rb,Rl ) I think you may also need clarified: Vin = constant Vb = Vl Vin...
28. ### Potential divider

Janitor, good example. Here's another. In real world electronics, small signal circuitry often operates best at a supply voltage lower than the rest of the tv, radio, etc. Since the load resistance of such a circuit is often nearly constant, Rb can be omitted, Rl becoming Rb in effect. Rt is...
29. ### Potential divider

The image link isn't working, but I'll try to explain. Rl the load resistance, Rt top resistor, Rb bottom, Vin, Vdrop (the voltage drop across Rt) and Vout. Vin is constant Vout = Rb / (Rt + Rb) When add your "lightbulb" Rb is replaced by a parallel resistor pair whose equivalent resistance...
30. ### Potential divider

Absolutely, the Vout will drop. The Vout proportional rule is only valid when equal currents pass through both resistors. In real world electronics, you always have to figure in the load of the circuit you're powering. And throw in a filter cap or inductor for good measure. :wink: