I Coriolis force, real or just an illusion?

[jbriggs444]

Can explain this left/nortwarth ,left/southward, with some animation or picture?
I don't understud that,I see only vertical correction when shoot est-west ,west-est.

axis of rotation is prependicular to latitude plane,so this platter is not tilted,so ho can horizontal deflection genereted?

In the temperate latitudes, the axis of rotation does not lie parallel to the surface on which you stand. The rotation vector (pointing out of the pole) has a non-zero component in the direction of the local vertical.

 

[A.T.]

I don't understud that,I see only vertical correction when shoot est-west ,west-est.

I would suggest you learn to apply Newton's Laws of motion in inertial frames. Judging by your cylinder example you have some misconceptions there.

Using rotating frames to analyze ballistic motion in a radial gravitational field, and expressing it in components relative to the curved surface is more complex.

 

[Delta2]

To directly answer the question of this thread:
IMO, Coriolis force cannot be classified as real. Real forces are the ones that belong to one of the following four categories
1). Gravitational
2). Electromagnetic
3) Strong Nuclear
4) Weak Nuclear

I don't think that Coriolis force belong to any of the above categories so it is not real, it is fictitious. The various phenomena and effects we observe and we attribute them to Coriolis force, are in fact due to the rotation (spin) of Earth around its axis. This rotation is real (of course !) but Coriolis force is not real.

 

[jbriggs444]

To directly answer the question of this thread:
IMO, Coriolis force cannot be classified as real. Real forces are the ones that belong to one of the following four categories
1). Gravitational

You might want to rethink that one. It's fictitious as well.

 

[Delta2]

You might want to rethink that one. It's fictitious as well.

Eh what , gravity is fictitious? Maybe according to relativity but not in classical physics

 

[Jeffery Winkler]

Not so impossible. You can still take a hovering helicopter from New York to London but it will take longer to get there.

Try the following experiment. Get out of your chair and stand up. Jump vertically up in the air. Did you land in the same place where you were standing before or off to the side because the Earth moved beneath your feet while you were up in the air? Try the same experiment on a moving train. You will land in the same place in relation to the floor as you were at before. You do not stop moving in relation to the ground outside just because you are not physically touching the train. Do you believe that if you did this experiment on the Concorde that you would be killed when you hit the back of the cabin?

 

[jbriggs444]

Eh what , gravity is fictitious? Maybe according to relativity but not in classical physics

That fact throws a bit of cold water on the question, no?

Does it really matter whether gravity is real or an illusion as long as we agree about the experimental results?

 

[Delta2]

That fact throws a bit of cold water on the question, no?

Does it really matter whether gravity is real or an illusion as long as we agree about the experimental results?

Er sorry I thought we were in the regime of classical physics here, the sub forum of this post is Classical Physics indeed. It is just not the same thing to say gravity is fictitious force (according to GR) as to say Coriolis is fictitious force, different meaning of fictitious I think. But anyway, gravity is considered to be one of the four fundamental forces of the universe in most books and papers for me gravity is a lot more real than Coriolis. Coriolis force is just a mathematical expression disguised as a force, the only thing real about it is the rotation of the system that seems to "generate" it, but a rotating system does not generate Coriolis force in the same way as the curvature of space time generates gravity.

 

[A.T.]

I shoot on est on 40th parallel,I see only vertical correction,shoot will come a little bit higher,because target appear to move down as Earth rotate...But my shoot do not cross other parallels...

Ignoring air resistance the bullet will move on an elliptical orbit in a plane that contains the center of the Earth. So it will obviously not stay above the 40th parallel, because the plane containing the 40th parallel doesn't contain the center of the Earth. Look up on how orbits in an radial gravitational field work

 

[jbriggs444]

It is just not the same thing to say gravity is fictitious force (according to GR) as to say Coriolis is fictitious force

It is the same machinery -- the mathematics of coordinate systems -- that is responsible for coordinate accelerations of free falling objects in arbitrary coordinate systems in general relativity and for the coordinate accelerations in accelerated coordinate systems in classical mechanics.

 

[Change in pressure]

Ignoring air resistance the bullet will move on an elliptical orbit in a plane that contains the center of the Earth. So it will obviously not stay above the 40th parallel, because the plane containing the 40th parallel doesn't contain the center of the Earth. Look up on how orbits in an radial gravitational field work

but our assumption is that in first 1000m bullet will go in straight line..

 

[A.T.]

Try the following experiment. Get out of your chair and stand up. Jump vertically up in the air. Did you land in the same place where you were standing before or off to the side because the Earth moved beneath your feet while you were up in the air?

If you could jump high enough, you would notice that you don't land in the same place.

 

[A.T.]

but our assumption is that in first 1000m bullet will go in straight line..

That's a nonsense assumption.

 

[Change in pressure]

If you could jump high enough, you would notice that you don't land in the same place.

Why than ground do not moving under hover helicopter,even if he hover 100years?

 

[jbriggs444]

but our assumption is that in first 1000m bullet will go in straight line..

Are you trying to come to grips with the difference between a bullet tracking a line of latitude versus a great circle versus a straight line?

Or with the difference between a bullet tracking a great circle path on the surface of a non-rotating spheroid versus a more complicated track on the surface of a rotating spheroid?

 

[jbriggs444]

Why than ground do not moving under hover helicopter,even if he hover 100years?

Air (and a helicopter pilot who compensates for the wind and for fuel shortages to stay in place relative to the Earth for 100 years).

Edit: In an attempt to make this relevant to the thread, let us ask: Why would one expect a helicopter to move relative to the ground? Coriolis does not enter in since the craft is motionless relative to the rotating earth. Centrifugal does not enter in since the slope of the geoid relative to a sphere perfectly compensates for the centrifugal force. The only reason one might expect a helicopter to stay in place over a rotating Earth is some sort of cartoon physics where the helicopter "enters an inertial frame" as soon as its wheels lift off from rotating Terra Firma.

 

[Change in pressure]

Air.

Air exist in bullet situation..

 

[jbriggs444]

Air exist in bullet situation..

And how many bullets do you see hovering in place for 100 years? What point are you trying to make?

 

[Change in pressure]

why she choose bullet path across others paralles(at 0:58) before shooting bullet,normally than would be horizontal correction because bullet travell a little bit north as well?
This is not good example of shooting on same latitude

 

[DrStupid]

IMO, Coriolis force cannot be classified as real.

That depends on the definition of "real".

Real forces are the ones that belong to one of the following four categories
1). Gravitational
2). Electromagnetic
3) Strong Nuclear
4) Weak Nuclear

That means if somebody finds a fifth fundamental interaction the corresponding forces wouldn't be real?

 

[A.T.]

Air exist in bullet situation..

Are you interested in deflection by the Coriolis force or by cross wind? Make up your mind.

 

[Change in pressure]

And how many bullets do you see hovering in place for 100 years? What point are you trying to make?

why do you think that air affect helicopter but bullet not?

Isnt strange that ground under helicopter do not rotate but ground under bullet is rotate?

I just mention this contradiction or maybe is just my own misconception...

 

[A.T.]

why do you think that air affect helicopter but bullet not?

Are you interested in deflection by the Coriolis force or by air?

 

[Change in pressure]

Are you interested in deflection by the Coriolis force or by air?

Here I just mention air as reminder that air is moving with Earth ,we are in one system,earth and air is one same system,I do not talking about cross wind etc...
I am interested only in coriolis...

You tell if you jump high enough that ground will move under you,so you will not fall down in same place.

That mean if you put dron that hover one year 15m above Earth in London,then new york will come under dron?
(assumption that wind is zero,so dron can stay in same place naturally..)

We know from experinecies that this will not happend,so can you explain why you fall down on diffrent place and dron will stay above london 1000years?
Isnt that in contradiction?

 

[Nugatory]

We know from experinecies that this will not happend,so can you explain why you fall down on diffrent place and dron will stay above london 1000years?
Isnt that in contradiction?

A drone or a hovering helicopter is using its rotors to hold itself in the same position relative to the air around it. Most obviously, the force of the air on the rotors is canceling the gravitational force so that the drone hovers instead of falling to the ground, but the force of the air on the rotors is also generating whatever sideways forces are needed to keep the drone over the same spot on the surface of the earth. (If you've ever sat next to a helicopter pilot holding a hover, you'll see that they're making constant small side-to-side adjustments with the control stick. A drone's onboard computer is doing the same thing).

A bullet is designed to be much less affected by aerodynamic forces, so we can usually analyze the trajectory of a bullet as if we're on an airless planet.

 

[Change in pressure]

A drone or a hovering helicopter is using its rotors to hold itself in the same position relative to the air around it. Most obviously, the force of the air on the rotors is canceling the gravitational force so that the drone hovers instead of falling to the ground, but the force of the air on the rotors is also generating whatever sideways forces are needed to keep the drone over the same spot on the surface of the earth. (If you've ever sat next to a helicopter pilot holding a hover, you'll see that they're making constant small side-to-side adjustments with the control stick. A drone's onboard computer is doing the same thing).

A bullet is designed to be much less affected by aerodynamic forces, so we can usually analyze the trajectory of a bullet as if we're on an airless planet.

imagine dron without electorincs which hold him in same place,so he only hover and wind is zero...will "new york" than come under dron or not??

 

[Nugatory]

imagine dron without electorincs which hold him in same place,so he only hover and wind is zero...will "new york" than come under dron or not??

You are asking what if the drone electronics are programmed to hold a constant altitude without doing any lateral positioning relative to the ground? It will remain at rest relative to the air around it. If the air around it is moving sideways relative to the ground (which we usually call "wind") the drone will be move sideways along with the air. If there's no wind then the air is not moving relative to the ground, so when the drone is at rest relative to the air it's also at rest relative to the ground so it will come down at the same spot as it took off. Basically, it's like a hot-air balloon being blown around by the wind.

Do note that this is completely unrelated to why when you drop an object in a moving vehicle it lands at the spot directly underneath your hand instead of further to the rear.

 

[russ_watters]

Why than ground do not moving under hover helicopter,even if he hover 100years?

[separate post]
Isnt strange that ground under helicopter do not rotate but ground under bullet is rotate?

The helicopter is stationary with respect to the Earth's surface by your own definition of the scenario. The bullet, on the other hand, is moving.

 

[A.T.]

I am interested only in coriolis...

Then why do you bring aerodynamics into it?

Isnt that in contradiction?

Do you understand why a hot air balloon drifts with the surrounding airmass, while a bullet is only slightly affected by wind?

 

[Change in pressure]

Then why do you bring aerodynamics into it?Do you understand why a hot air balloon drifts with the surrounding airmass, while a bullet is only slightly affected by wind?

Force= pressure x area ...so balloon have bigger area so wind affect balloon more...

can you explain me why if you jump high enough(like you said) Earth under you will move but small cheap dron which do not have electronics that hold him in same place and wind is zero,stay in same place=earth is not moving under him ?

 

[RPinPA]

Force= pressure x area ...so balloon have bigger area so wind affect balloon more...

can you explain me why if you jump high enough(like you said) Earth under you will move but small cheap dron which do not have electronics that hold him in same place and wind is zero,stay in same place=earth is not moving under him ?

If you are moving with the atmosphere, you also move with the Earth's surface.
If you are moving under the influence of gravity and not affected by the atmosphere, then you are not moving with the Earth's surface.

The drone "hovering" is fixed in the atmosphere. It moves with the surface.

 

[A.T.]

Force= pressure x area ...so balloon have bigger area so wind affect balloon more...

And do you understand why a passively hovering helicopter also drifts with the surrounding airmass?

 

[jbriggs444]

Force= pressure x area ...so balloon have bigger area so wind affect balloon more...

can you explain me why if you jump high enough(like you said) Earth under you will move but small cheap dron which do not have electronics that hold him in same place and wind is zero,stay in same place=earth is not moving under him ?

The Earth moves in either case. However, in the one case (drone, helicopter, weather balloon), the device is moving with the air above and remains as fixed in place relative to the Earth as is the air above. And in the other case (bullet), the device is on a ballistic trajectory and is not fixed to drift with the air.

 

[Change in pressure]

The Earth moves in either case. However, in the one case (drone, helicopter, weather balloon), the device is moving with the air above and remains as fixed in place relative to the Earth as is the air above. And in the other case (bullet), the device is on a ballistic trajectory and is not fixed to drift with the air.

so if I jump high enough in london I can fall down in new york?
or if I throw ball down from very high house(50km) in london,,ball will touch ground at China?

(that coriolis say)

 

[Bystander]

so if I jump high enough in london I can fall down in new york?
or if I throw ball down from very high house(50km) in london,,ball will touch ground at China?

Yes, and yes.

 

[jbriggs444]

A ball thrown straight down from only 50 km will not land far from the base of the tower. The tower would need to be much higher to have the landing point be in China. Probably less than 22,000 miles, but still plenty high.

 

[A.T.]

so if I jump high enough in london I can fall down in new york?

Does it matter if it's London and New York? The point is that the location will be different.

or if I throw ball down from very high house(50km) in london,,ball will touch ground at China?

Not high enough to get from London to China.

 

[FactChecker]

so if I jump high enough in london I can fall down in new york?
or if I throw ball down from very high house(50km) in london,,ball will touch ground at China?

Your initial velocity would need to include the velocity you have due to the rotating earth. Also, any aerodynamic effects would need to be accounted for. In the case of a ballistic missile, the aerodynamic effects may be small. In the case of an artillary shell or a bullet which does not leave the atmosphere, the aerodynamics effects are probably significant.

 

[Change in pressure]

A ball thrown straight down from only 50 km will not land far from the base of the tower. The tower would need to be much higher to have the landing point be in China. Probably less than 22,000 miles, but still plenty high.

hause high 50km at equator

C(equator)=2r x 3.14 = 2 x 6371km x 3.14 =40 009km / 24h = 1667km/h

C(ball)= 2r x 3.14 = 2 x (6371km+50km) x3.14 =40323km /24h = 1680km/h
1680-1667=13km/h

top of hause travel 13km/h faster then bottom...

so this 13km/h is additional velocity which ball have in east direction

with this information we can calcualte how far east will ball hit the ground....

 

[Change in pressure]

very nice lecture but this toillet paper open becuase of air pressure,not coriolis. :)

 

[jbriggs444]

hause high 50km at equator

C(equator)=2r x 3.14 = 2 x 6371km x 3.14 =40 009km / 24h = 1667km/h

C(ball)= 2r x 3.14 = 2 x (6371km+50km) x3.14 =40323km /24h = 1680km/h
1680-1667=13km/h

top of hause travel 13km/h faster then bottom...

so this 13km/h is additional velocity which ball have in east direction

with this information we can calcualte how far east will ball hit the ground....

Given the time of fall, yes. Note that the proposed calculation does not depend at all on the radius of the earth. The 6371 cancels out.

But that's the inertial frame calculation. In the rotating frame there is no difference in velocity. The explanation for the deviation in the landing point derives from Coriolis instead.

 

[A.T.]

so this 13km/h is additional velocity which ball have in east direction

with this information we can calcualte how far east will ball hit the ground....

Approximately. For a more precise calculation in the inertial frame you would find the intersection of the elliptical orbit with the curved surface.