On Saturday I was taking balloons to my neice for her birthday party

  • Context: High School 
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Discussion Overview

The discussion revolves around the behavior of balloons and other objects during turns, particularly focusing on why balloons move towards the center of a turn while other objects, like sand in water, also seem to exhibit similar behavior. Participants explore the underlying physics concepts, including buoyancy and centrifugal forces, in both air and water contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant observes that balloons move towards the center of a turn, questioning why this occurs when most objects move away from the center.
  • Another participant explains that the movement of balloons can be attributed to the air inside the vehicle displacing towards the outside of the turn, causing the balloons to move inward.
  • A different viewpoint introduces the principle of equivalence, suggesting that during a turn, the centrifugal acceleration can be perceived as a gravitational force pulling objects towards the center.
  • One participant presents an analogy with swirling water and sand, noting that while heavier sand is expected to move outward, it instead moves towards the center, prompting further inquiry into this behavior.
  • Another participant argues that the behavior of sand cannot be explained by buoyancy, as one would expect it to move outward, yet it does not, raising questions about the underlying principles at play.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of balloons and sand during turns, with no consensus reached on the explanations for the observed phenomena. The discussion remains unresolved regarding the mechanics behind the movement of sand in swirling water.

Contextual Notes

Participants reference concepts such as buoyancy and centrifugal forces, but the discussion does not clarify the assumptions or definitions underlying these concepts, leaving some points open to interpretation.

Cod
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On Saturday I was taking balloons to my neice for her birthday party when I noticed something that I'd never noticed before. When I took a turn, the balloons were moving towards the center of the turn. Whenever taking a turn while driving, I realize that most objects move away from the center of the turn. So this brings a question to my mind: Why is it that the balloons went towards the center of the turn instead of away from the center? And are balloons the only objects that will do this?
 
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He balloons are lighter than air. What you actually see is the effect of the air inside the vehicle sloshing over to the outside of the turn, displacing the balloons toward the inside. A similar effect can be seen with a bubble level. Take one and on a smooth surface accelerate it forward. You will see the bubble go forward as if it has negative mass. Which in a sense it does.
 
Alternatively, you may want to consider applying the principle of equivalence. When we make a turn, the centrifugal acceleration we experience is directed away from the centre of the turn. Now, using the principle, we can also think it as if we are not moving/turning at all, but there's a gravitational acceleration in the direction away from the centre of the turn.

Now, why does a helium balloon float? It is due to the lower density of helium compared to air, pushing it from the ground. So in that case above, the balloon will 'float' towards the centre of the turn. This is also another way how you can see the problem.
 
Good explanations, I think.

But now this. I have a bucket with water and I swirl the water around, So it's also making that same turn. Now, I drop in some sand grains, heavier than water So in analogy to the balloons, you'd expect the sand to swirl towards the outside of the turn, but instead the sand at the bottom also moves to the centre of the turn.

Now, any theory about that? :smile:
 
water is diffrent, it would be like a whirlpool type of thing, I know there's a diffrent name for it, well anything that's heavy will go to the center and sink, like if the grain of sand was a ship.
 
Originally posted by Andre
Good explanations, I think.

But now this. I have a bucket with water and I swirl the water around, So it's also making that same turn. Now, I drop in some sand grains, heavier than water So in analogy to the balloons, you'd expect the sand to swirl towards the outside of the turn, but instead the sand at the bottom also moves to the centre of the turn.

Now, any theory about that? :smile:


This is the same principle, the lighter air would go torwards the ouside and the heavier sand torwards the inside.
 
Not really, the lighter balloons are forced to the centre of the turn because buoyancy also works for centrifugal forces. Now the heavier sand that also moves to the centre of the turn cannot be explained by buoyancy. With that effect you would expect the sand moving to the outside of the turn. But it isn't. Why?
 

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