Coriolis force, real or just an illusion?

[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.