Coriolis force - Question about sign

In summary: It could have been written as -2v x ω and then there would be no minus sign. Either way, it's just a matter of convention and doesn't change the physics.
  • #1
Curious2013
4
0
Dear all

I have a question concerning the Coriolis acceleration expression. I learned it as Ac = -2ω x v, where ω is the vector which indicates the rotation axis direction of Earth and v the velocity of a body that I want to check the Coriolis effect on.

My question: where the minus sign comes from? As far as I understand, it depends on what reference frame I use (inertial or non inertial - the minus comes from the latter, like the Earth, in my conception). Am I correct?

Thanks in advance!
 
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  • #2
Curious2013 said:
Dear all

I have a question concerning the Coriolis acceleration expression. I learned it as Ac = -2ω x v, where ω is the vector which indicates the rotation axis direction of Earth and v the velocity of a body that I want to check the Coriolis effect on.

My question: where the minus sign comes from?
You can swap ω and v, and the minus sign is gone:

-2ω x v = 2v x ω

Curious2013 said:
As far as I understand, it depends on what reference frame I use (inertial or non inertial
The Coriolis force exist only in non inertial frames.
 
  • #3
The minus sign is there because humans made the arbitrary decision to use right-handed coordinate systems rather than left handed ones.

The Coriolis force is just a consequece of Newton's laws of motion. The physics doesn't depend on what frame you use to describe it, or whether the frame is inertial or non-inertial. The details of the math depend on those things, but "the map is not the country", and similarly "the math is not the phyiscs".
 
  • #4
AlephZero said:
The minus sign is there because humans made the arbitrary decision to use right-handed coordinate systems rather than left handed ones.

no, it would still be there, because you'd still need v = ω x r :wink:

(btw, this is a duplicate thread to https://www.physicsforums.com/showthread.php?t=659387)
 
  • #5
AlephZero said:
The minus sign is there because humans made the arbitrary decision to use right-handed coordinate systems rather than left handed ones.
To me it seems more like it's the arbitrary decision to have ω first in the term.
 

1. What is the Coriolis force?

The Coriolis force is a fictitious force that appears to act on objects in motion on the Earth's surface due to the Earth's rotation. It is caused by the rotation of the Earth and the inertia of the object.

2. How does the Coriolis force affect objects?

The Coriolis force causes objects to appear to deflect from their straight path of motion on the Earth's surface. In the Northern Hemisphere, objects will appear to deflect to the right, while in the Southern Hemisphere, objects will appear to deflect to the left.

3. What is the direction of the Coriolis force?

The direction of the Coriolis force depends on the direction of motion of the object. In the Northern Hemisphere, the force will always act to the right of the direction of motion, while in the Southern Hemisphere, it will act to the left of the direction of motion.

4. How does the Coriolis force impact weather patterns?

The Coriolis force plays a significant role in the formation and movement of weather systems. It causes low-pressure systems to rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere, while high-pressure systems rotate in the opposite direction.

5. Is the sign of the Coriolis force the same in both hemispheres?

No, the sign of the Coriolis force is opposite in the Northern and Southern Hemispheres due to the opposite rotation of the Earth. In the Northern Hemisphere, it is a positive force, while in the Southern Hemisphere, it is a negative force.

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