B Slow Motion Appearance of Flags: Fluid Dynamics or Perceptual Illusion?

[metehansure]

Why do flags appear to move in slow motion when they flutter in the wind, even though the wind can be strong and variable? Is this perception purely psychological, or are there physical principles (such as fabric dynamics or fluid mechanics) that contribute to this seemingly slow, graceful motion?

 

[Chestermiller]

What have you done to analyze this problem and to research it?

 

[Lnewqban]

Welcome!
Huge airplanes also appear to move in slow motion.

 

[russ_watters]

They flutter slowly in a slow wind and fast in a fast wind....

 

[metehansure]

What have you done to analyze this problem and to research it?

I’m trying to build up my understanding of physics concepts by asking questions that emerge from everyday observations. I tried looking up 'flag motion fluid dynamics', but most of what I found was overly technical. That’s why I thought this forum might help me connect intuition with actual physics.

 

[Baluncore]

Why do flags appear to move in slow motion when they flutter in the wind, even though the wind can be strong and variable?

As the wind passes a flag pole, it deviates alternately to the left and right, forming a "Karman street". The flag lies between the air that moves down one side of the pole, and the air on the other. It therefore shows the position of the boundary between the alternating vortices, as they move downstream with the wind.
https://en.wikipedia.org/wiki/Kármán_vortex_street

 

[metehansure]

As the wind passes a flag pole, it deviates alternately to the left and right, forming a "Karman street". The flag lies between the air that moves down one side of the pole, and the air on the other. It therefore shows the position of the boundary between the alternating vortices, as they move downstream with the wind.
https://en.wikipedia.org/wiki/Kármán_vortex_street

Thank you so much for your clear and detailed explanation.

 

[sophiecentaur]

but most of what I found was overly technical.

Such is life / Physics.