I love your work BA but I think either I misunderstand you or you got this one wrong. To wit:
The Sun, in its apparent motion in the sky, travels along the ecliptic crossing the path of the Moon’s orbit (at its nodal points) twice a year. (Well, actually it can cross it three times in a calendar year but that’s not really important here.) Each time, six or so months apart, that the Sun crosses the Moon’s path in the sky there is an opportunity for an eclipse. It turns out that there will be at least one eclipse and occasionally two at each and every one of these opportunities.
Now, of course, most of these will be partial eclipses and maybe about 70% will be over the ocean somewhere. (I guarantee you nobody’s going to pay for a cruise out to sea to watch 10% of the Sun blocked out!) But fully a quarter, or so, will be total eclipses of varying duration.
To sum up, there are at least two, and as many as five solar eclipses per year. It’s just that most are inaccessible and usually partial eclipses.
Now, of course, if you were pointing out why there isn’t a total solar eclipse every month then I offer this as merely an addendum.
Here’s a quick and dirty explanation regarding particles, forces and “atom smashers”.
A current theory known as the “standard model” includes particles that are said to transmit forces. (I believe these are called “gage bosons”, but my particle physics is rusty.) For example, photons transmit the electromagnetic force. There are similar particles for other forces, too. It turns out that photons have no mass, but other bosons do. The math behind the standard model predicted those masses and they were verified experimentally.
Which brings us to atom smashers. Particle accelerators (the correct term) do just that - accelerate particles. The idea, though, is not just to “smash” them and “see” what’s inside - it is to give them high energy and create exotic particles that don’t exist naturally or long enough to observe. By smashing them together, of course. Various detectors are used after the collision to see what was created. Now, since mass is equivalent to energy (E=mc^2, etc., etc.) high-energy collisions create high-mass particles.
Which brings us to gravitons. In the current form of the standard model, doing math to find the theoretical mass of a graviton yields a relatively large number. Larger, in fact, than any current partical accelerator can generate. That is why gravitons have not been “found” yet. This is assuming that the standard model is correct, too.
I think that the VLHC (very large hadron collider) in the works at Fermilab should be able to reach the required energy, but I don’t have any numbers for you. I strongly suggest reading The God Particle by Leon Lederman. It’s a little dated by now, but it’s incredibly easy to read for this type of material and refers to your exact question.
So much for “quick and dirty”. I’m sure there are other people on this board who know more about this than me, so don’t take it as gospel.
Bernoulli’s Theorem:the sum of the pressure and the product of one-half of the density times the velocity squared is constant along a streamline for steady flow in an incompressible nonviscous fluid at constant height.
Looking at this, I suspect that in the ideal case the fact that the ball is spinning shouldn’t have any effect at all - the streamlines would be identical above and below and would have the virtually the same pressure (there is a small difference in height). However, we aren’t looking at the ideal case - air is compressible and viscous and we have to take that into account.
For a ball with backspin:
1)The top surface is trying to drag air from the front of the ball to the back, and the resulting decrease in density means lower pressure above the ball.
2)The bottom surface is trying to drag air from the back of the ball to the front, and the resulting increase in density means higher pressure below the ball.
I suppose you could say that the streamlines on top are actually moving faster and that the streamlines on the bottom are actually moving slower, but it’s not really as satisfying when you put it that way.
The graviton is expected to be massless, like a photon. Maybe you’re thinking of the Higg’s Boson. Also, I don’t think gravitons are considered part of the Standard Model (yet).
No, I was correct. The tilt of the Moon’s orbit with respect to the SUn’s path on the sky means that they usually miss each other by a long ways. I didn’t talk about the nodes because that wasn’t the point I was discussing. A good website with a discussion of all this is Nick Strobel’s Astronomy Notes at http://www.astronomynotes.com.
Far be it to disagree with The Master, but unless the bullet is fired with a tremendous muzzle velocity the curvature of the Earth is immaterial. There isn’t enough ground covered for it to matter.
I wonder if the spinning bullet might generate a lift, however, like a golf ball? That might force it up or down. Hmmm.
Seems unlikely, since the bullet would be spinning about an axis parallel to its line of travel, and thus would have no more of a tendancy to rise than it would have a tendancy to drop (or go left or right, for that matter).
Ah, excellent point. My initial suspicion was that nothing would happen, or else guns would have to be adjusted for it when aiming. I had no gun cite though. Haha. Ahem.
Well, Bernoulli’s principle is passe’ for explaining the lift of an airplane wing, so I’ll try to take a stab at it from a more intuitive level.
If you hit a ball with backspin, its spin is grabbing air from the top surface, and throwing that air downwards off its trailing end. The air tends to stick to the surface, so that lets it throw the air in the direction of how the trailing end is spinning. The momentum of the air thrown downward behind the ball is exactly equal to the lift momentum given to the ball.
You got that right ZenBeam, that’s what “The God Particle” was all about, not the graviton.
The graviton can’t be part of today’s standard theory because QM and GR can’t be reconciled. That’s what String theory is all about. The graviton is a boson with spin two and it automatically pops out of the ST math, but unfortunately the math is so difficult the theory is a long way from being anything but a possibility.
So… do scientists know (or think they know) the particle/medium/ether/orgone, or whatever the appropriate term is, for the method by which gravity acts with force over a distance. If I am a wandering asteriod and I feel the tug of Sol’s gravity pulling me toward it WHAT is yanking on my mass and making me change direction and HOW is it tranporting this effect/force over a distance.
As a side question if the gravition is supposedly “massless”, how can a massless particle exert of force on mass per the effect of gravity?
I fear that I am mis-understanding something basic with
this “show me the particle/wave” notion regarding the effect of gravity but doesn’t it have to reduce to some form of quanta at some point?
How Planes Don’t Fly - the problem isn’t really with Bernoulli’s Principle, it’s with the bizarre “principle of equal transit times.”
I’ve got a bit of a problem with your explanation, and not just because I’m emotionally attached to mine. If the spinning ball is stationary the momentum transferred upwards is going to be equal to that transferred downwards yes? It’s not at all clear that motion in a direction where the spin is “backspin” is going to result in a net downwards tranfer of momentum.
Well as an ex Pitts Special pilot I may be able to help here. There are a couple of critical things involved in an aircraft wing producing lift.
It’s shape (ie more curved at the top than the bottom)
The airspeed
The angle of attack.
Now it’s angle of attack or AoA which most people don’t really consider. The AoA is the angle between the chord of the wing and the relative airflow. The chord being a line running from the leading edge to the trailing edge of the wing when viewed in cross-section.
A wing requires some AoA to produce significant lift. It is said that
lift = airspeed x AoA
therefore, 0 AoA = 0 lift. Typically in level flight at cruising speed a wing’s AoA will be about 4 degrees and as the wing’s AoA approaches between 15 - 20 degrees (depending on wing shape) the airflow becomes disrupted over the top of the wing and it becomes stalled, it stops producing lift.
Essentially AoA creates high pressure under the wing by presenting some of the undersurface of the wing to the airflow. Next time you’re in a car, open the window and stick your hand out like a wing, now tilt your hand upwards slightly, what happens? It gets forced up ie it has become a lifting surface relying on Angle of Attack alone.
Because AoA has a much greater affect on lift than the shape of the wing an inverted wing can overcome the non ideal shape (ie it is now more curved at the bottom) by flying at a higher AoA.
Purpose built aerobatic aircraft such as the Pitts Special often have a symmetrical wing section where the upper and lower curve is identical allowing the wing to fly upside down almost as good as right side up. I say “almost” because there are some other factors which degrade performance slightly in inverted flight.
So it turns out that having a wing shaped in the traditional longer-over-the-top-shorter-across-the-bottom way is not critical for flight. It does produce a better lifting surface though and so is used for the vast majority of aircraft.
Fast jets have a totally different wing shape BTW where the thickest part of the wing is close to the middle of the wing when viewed in cross section.
Nothing is yanking on your mass. GR says that mass/energy causes space to have an intrinsic curvature so, in effect, your in freefall and won’t feel a thing.
A particle doesn’t have to have mass in order to have momentum. For instance the momentum of a photon = (planck’s constant times the frequency) / c.
If the ball is in motion, then its surface pulls air from the front side, along the direction of spin, and throws it back on the trailing side in that direction. It doesn’t do this when it’s not in motion.
And the reason that Bernoulli is not favored for an explanation of airplane wing lift is more than just the equal-transit-time wrong assumption. It’s also that you’re using an abstract, non-intuitive equation (Bernoulli) instead of a very intuitive, simple explanation of action and reaction, which works perfectly well for high school and early college.
Well, it doesn’t do only that, but it does do it. A spinning stationary ball is going to be throwing off air in every direction (up, down, backwards, forwards, etc.) Why when the ball is in motion the contributions of every other direction can be ignored is a mystery to me.
I believe I said as much in my first post: “it’s not really as satisfying when you put it that way.” My explanation doesn’t depend on Bernoulli’s Principle.
My question is kind of a continuation of whatami’s point made just above regarding the horizontally fired bullet. There is a certain velocity a bullet can attain that would allow it to fall in a curve parallel to the earth’s curvature and, theoretically, never land. I imagine this scenario conveniently dismisses the effects of friction on the projectile. Anybody know what the velocity is? Aren’t the space shuttle and, I guess, all satellites doing the same thing… falling toward the earth at a horizontal speed great enough to significantly delay their vertical impact?