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If it implies tumbling I could see a higher drag from the smooth bore vs rifled. The spin imparts stability and keeps the bullet in a pointing direction of flight while tumbling will expose more surface area if the round turns pointing sideways to flight

Why is Titan the only moon with a substantial atmosphere?

Why does Ganymede have a global magnetic field, while so many other large, similarly massed moons don't?

>what happens to the matter around a vacuum?

Matter in a vacuum has no forces exerted on it.

>What forces are created by the pressure differential?

Pressure is just Force / Area.

Pressure ( in this example ) is the result of the summation of forces of gases bouncing off of a surface. There is very high pressure at the front of the shell, and very low pressure at the rear of a shell when fired.

>If you found a way to decrease the pressure differential, what would happen to those forces?

You can reduce drag if you change the shape of the shell. If you have more pressure at the rear of the shell the net force on the shell is reduced. You can do this with a boat-tail shell.

>Which one would exert a greater net gain in speed, the equalization of the pressure differential or the ejection of mass to fill said void in this particular scenario?

The gas sent out of the rear of the shell does not act like a rocket. In a bleed gas shell the gas is going nearly the same speed as the shell, and is trapped there for multiple interactions. The trapping of this allows the gas to exert a pressure onto the shell. If your force diagram model has this gas as part of the shell you have a new drag coeffienct, if you model the shell alone then you have this gas exerting a force ( or a pressure over an area ) on to the shell.

This NASA page says:

> The greater Earth’s axial tilt angle, the more extreme our seasons are, as each hemisphere receives more solar radiation during its summer, when the hemisphere is tilted toward the Sun, and less during winter, when it is tilted away.

It has this to say about the 26k year cycle you're referring to:

> Axial precession makes seasonal contrasts more extreme in one hemisphere and less extreme in the other. Currently perihelion occurs during winter in the Northern Hemisphere and in summer in the Southern Hemisphere. This makes Southern Hemisphere summers hotter and moderates Northern Hemisphere seasonal variations

So I guess I still have the same question, but complicated by the fact that models would have to account for a different effect in different hemispheres.

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Actually the tilt decreasing would increase the rate of extreme weather events. Every 26000 years or so seasons on the planet flip North to South. Or winter in the US would be in July, and Summer in Australia would be in July.

The most recent was about 18000 years ago now (that allowed people to traverse the Bering Strait and settle North and South America from Asia), or the last ice age we are currently coming out of. In another 8 to 10K years we will likely re-enter a minor ice age. This is due to the sheer volume of landmass in the North vs the South, and as such Snow sticks better...reflects more light back...so it stays colder, for longer, more snow, etc etc etc.

So as the tilt declines air and sea currents become more tropical (focused between the tropics and the equator) and as such more freakish weather can pop up almost anywhere at any time due to the increased amount of water entering the atmosphere due to the tropical heating effects on waters that didn't really experience it before.

As this procession continues weather patterns normalize as the system balances....and then like 13000 years later it starts to repeat as the function repeats itself in the inverse.

As for the measurements themselves based on tilt, they can be factored in, but it's largely irrelevant given the time scale of the procession 26000 years or so is a long ass time...and basically irrelevant for what happens in the next few hundred years.

For the most part you going to have same or similar weather right up until a couple centuries before it flips and starts going back the other way.

(If this makes sense. Explaining these types of procession can be tough at times.)

Out of curiosity, in your force diagram, what happens to the matter around a vacuum? What forces are created by the pressure differential? If you found a way to decrease the pressure differential, what would happen to those forces? Which one would exert a greater net gain in speed, the equalization of the pressure differential or the ejection of mass to fill said void in this particular scenario?

In real world application Photons lose energy all the time colliding and scattering off objects.

If a Photon can travel a straight line in a vacuum it will travel that line forever without loss of Energy.

However in space for example there is just so much stuff out there (including other photons) to collide into that photons are constantly be redirected rerouted or absorbed by other particles and objects.

This is what leads to depletion of energy, adjustment of wavelengths that is call red shift.

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Is Gravity just a by product of Electromagnetic Force and its relationship between objects, or is it probably its own thing...we know magnetically polarizing things can "beat*" Gravity. (Floating art using magnets for example.)

• I know it's not beating Gravity it is using force to resist effect of gravity, but to make objects float and not just fly off would require both forces to be comparable would it not?

Everything emits electromagnetic waves, everything is impacted by Gravity. Both Gravity and Electromagnetism decay at 1/R^2.

I do know that GEM (Gravitoelectromagnetics) is a fairly new (relatively speaking) concept of physics? (Maybe mid 1800s?).

Googling just gives me an answer of "they aren't the same thing because we have no evidence they could be (is this true or just a lazy take because we just dont know?)

Curious me has to ask. If both forces protrude "forever" and become their strongest at a certain "break point" and both decay at the same 1/R^2 Rate, and both impact all objects are they effectively the same thing?

The magnetism (haha) between the two seems pretty dang strong.

Is it?

Great question! The answer is both, and it depends on the geometry of the specific river - not to mention how it interconnects to branching/merging paths of other river segments to really complicate what's going on.

I've done a fair amount of white water kayaking, and we always pay attention to current rainfall conditions, and even if an upstream dam has been recently released. High water conditions can be very fun as some stretches flow faster and make certain rapids larger. But I've also seen high water conditions completely wash out a drop to feel like a speed bump.

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Many parts to this question:

Q. How do we know that the universe expansion is really the explaination for the observed redshift of light from stars.

1. As i understand it, space is a quantum soup of virtual particles. Shouldn't these virtual particles able to absorb light energy?
2. is it possible the magnetic and electric permeability of free space is changing over time? Wouldn't that change light waves in space?

Q. If one has crossed the event horizon of a black hole, is one traveling faster than light and thus going backward in time wrt the outside universe on the other side of the event horizon?

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Why isn't the amount of energy absorbed by a photon striking a target based on the distance traveled? Eg, if I have a 420nm wavelength with a target 420nm from the source. Polarization filters in place.
Why is the same amount of energy absorbed if it is 210nm from the target vs 105 or 215nm?

Every single point of mass has a gravitational field, including tiny elemental particles such as protons or neutrons. The force of attraction between two masses is governed by Newton's law of gravitation, such that larger masses attract smaller ones and mass begins to gather in small pockets, "it's getting closer together" and then, eventually, "it's a star!"

TLDR: Yes, the gases themselves are gravitational sources.