# Search results

1. ### What does statistically significant mean?

That's really clear...
2. ### Proof of this limit formula for e

The above "solutions" are all tautologies. They all assume that e exists and is the base of natural logarithms. Now, this is true, but the proof of this is outlined at http://planetmath.org/convergenceofthesequence11nn, I have found no other site with this proof. Essentially done in two...
3. ### B Suspended Mass

Just to note that the F-4 (Phantom Jet) of the 1950s and later, which looked like a brick could fly because it was given enough power.
4. ### B Suspended Mass

Thank you, Nugatory I think "I've got it." If the "mass" were kept aloft by an airfoil (vertical lift generated by horizontal motion), i.e., translating induced drag to vertical lift by the airfoil, is theoretically possible with a super large airfoil of no weight itself to generate large lift...
5. ### B Suspended Mass

Is there any way to convert horsepower into pounds thrust?
6. ### B Suspended Mass

Don't want to start a "fight."
7. ### B Suspended Mass

Aware that work done on the mass is zero. BUT it won't stay up on its own. Where does the force come from? How is it generated?
8. ### B Suspended Mass

Still, no answers posted. Only vague generalities.
9. ### B Suspended Mass

To maintain a 550 lb mass in the air not touching the ground at sea level (radius of Earth is 4000 miles), what is the expenditure of energy required given perfect efficiency of the process?
10. ### B Does red-shifted light cause expansion of space?

@phinds - Never thought of that.
11. ### B Does red-shifted light cause expansion of space?

Red shift is a result of the expanding universe, not the cause of it. Basic Doppler wave mechanics. Must keep the cart and horse in the right order. Question is did the original singularity have infinite energy? This is possible mathematically (1/zero). If it did, the universe will never...
12. ### Tissue transplantation

I hate to use the Internet as a reference but this is a simplistic one. It paraphrases what the more technical references state: Home Treatment / Support Long-Term Follow-Up Frequently Asked Questions Understanding graft-vs.-host disease ShareLONG-TERM FOLLOW-UP Understanding...
13. ### Tissue transplantation

Works the other way. The tissue that does the reacting is the donor tissue (the female tissue.) Hence the F > M transplant will result in a greater reaction (GVH.)
14. ### Tissue transplantation

Sounds like GVH disease would be more common in F > M transplant due to extra X and more potent immunologic response by female tissue and T-cells.
15. ### Tissue transplantation

How can one transplant a (donor) tissue to a recipient allograft and have it "take" if the donor and recipient are of different sex? They are automatically genetically different which can never be broached.
16. ### Is it possible to get down by throwing hands upwards?

The external force comes from the conversion of potential energy to kinetic energy. Imagine taking a deep breath. Then being placed in space. Then forcibly exhaling and this action-reaction would push the individual the opposite direction of the exhalation. Similar to a CO2 cartridge in...
17. ### Is it possible to get down by throwing hands upwards?

Remember, the body (cats, too) have "potential energy" in the form of ATP and actin which can be expressed as work and create motion. The actual motion is dependent on the living tissue. F = ma. s = (1/2 ) at^2. Depending on t [the time of application of the force] one can back calculate the...
18. ### Change in mass of a soda can

LOL! Not at you but at the kids. Devious minds!
19. ### Is it possible to get down by throwing hands upwards?

Actually, you could move by expending work. Not enough space or time here to go into the classical Newtonian physics regarding this. The body does have energy (work) available in the form of ATP, etc. which muscles can use to generate motion and can be directed. With that, motion can be created.
20. ### Change in mass of a soda can

You are quite right. The author himself noted much condensation on the cans. Initially the can would be weighed before condensation. After the can was opened and while 0.2 Gm of weight gain occurred initially from the condensation. This would evaporate in the hour described and the weight...
21. ### Change in mass of a soda can

The only possibility here, if this experiment is truly reproduceable, is the upward "force" of the escaping CO2 gas with the reaction of downward force on the can. To wit, if one takes a CO2 cartridge and punches a hole in one end the cartridge will accelerate in the opposite direction. Such...
22. ### Heat engine that violates Second law of thermodynamics?

Contrite? You don't have to be remorseful for anything. There must be some proof out there that the Carnot parallelogram gives "the most for the least"'(the most efficient). My guess is that by drawing any other diagram that produces more output (higher efficiency) violates some basic...
23. ### Heat engine that violates Second law of thermodynamics?

You DID answer the question earlier in the thread by, essentially stating that no PV diagram can violate the Second Law. Carnot proved that himself in the 1820s although he didn't know what the Second Law was.
24. ### Heat engine that violates Second law of thermodynamics?

@stedwards. It appears that Amin2014 doesn't know where to begin otherwise he/she wouldn't ask the question. It also appears that the real question is: is there a PV diagram that violates the Kelvin-Planck hypothesis? Do you (stedwards) know of any such diagram? I am not a thermodynamics...
25. ### Heat engine that violates Second law of thermodynamics?

Any heat engine that is more efficient than Sadi Carnot's cycle inherently requires 1). Either a permanent T1 (elevated heat source by the environment, not from the fuel source( Or 2). A mythical T2 (heat sink temperature) below the ambient environmental temperature by some magical means No...
26. ### The Safest Thing to Do On an Open Field During Lightning

She is s-o-o-o skinny - ugh!
27. ### What's the universe collapsing into?

According to William Thomson (Lord Kelvin) who predates Planck et al, entropy is always increasing implying that the total energy level will asymptotically approach some unspecified universal mean of total neutrality in some very distant future. Of course, Lord Kelvin was a Creationist (not the...
28. ### The Safest Thing to Do On an Open Field During Lightning

@Evo. It seems like the first if your references answers the questions: there it is stated: " As the negative charges collect at the bottom of the cloud it forces the negative charges in the ground to be forced away from the surface. This leaves the ground positive. A streamer of negative...
29. ### The Safest Thing to Do On an Open Field During Lightning

@Evo. Then, in your understanding, what are the "positively charged particles" which travel upward (in the streamer) towards the stepped ladder? They are not electrons, they are not positrons. Maybe they are positively charged ions or atomic nuclei after their electrons have been stripped...
30. ### The Safest Thing to Do On an Open Field During Lightning

@Evo. I know a woman (a red head, naturally) who has been struck by lightning three times. She is crazier than a hoot owl but I am positive that her craziness preceded her lightning strikes. She had to be that way as there is no earthly explanation as her complete lunacy, although the good...