Will a Wire Hanger Bowl Hold Water?

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In summary: And I have given examples too.In summary, the question is whether a wire hanger bent into a bowl shape and rotated at a high speed could hold water without it flying upward and out of the bowl. The consensus is that the rotational speed would not be fast enough to hold water, as demonstrated by the example of a bowl with a hole in it. There is also discussion about the possibility of the wire holding a solid object, but this would not be a stable situation and would essentially function as a blender.
  • #1
robstrous
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Me and a friend had an argument. Say you had a wire hanger and bent it into the first shape shown in the attachment (a straight portion and then the rest curved into a half "U"). You attach the straight portion to a machine that rotates the object at a very high speed and creates a bowl shape with the half U portion, as shown in the second half of the picture. The argument is this: could the rotational speed of the hanger be fast enough to hold water, or would it fly upward and out of the created bowl?
 

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  • #2
It cannot hold the water. What an idea!

Suppose you have an actual bowl spinning but with a hole in it. The water will obviouly come out of this hole due to the centifual force (and gravity). Your roating hanger is nothing but a bowl with a big big hole.
(Or a hole with a broken bowl!)
 
  • #3
robstrous said:
Me and a friend had an argument. Say you had a wire hanger and bent it into the first shape shown in the attachment (a straight portion and then the rest curved into a half "U"). You attach the straight portion to a machine that rotates the object at a very high speed and creates a bowl shape with the half U portion, as shown in the second half of the picture. The argument is this: could the rotational speed of the hanger be fast enough to hold water, or would it fly upward and out of the created bowl?

A good question! I assume you're thinking the viscosity of the water is large enough to hold it in place till the wire comes around again. You might think of using a rotating shape that has some restorative force (kind of like a propeller blade) since any fluid that "droops" will not be picked up on the next rotation unless you have a fluid much closer to molasses on a cold day.

You might look at common kitchen mixers to see how your idea works. In fact, if you're willing to make a little mess, you can come pretty close to your answer experimentally. Keep up this kind of thinking - this is the kind of strange question Richard Feynman was famous (infamous?) for.
 
  • #4
other perspective: could this wire-cup hold a tennis ball, or a pingpong ball?
 
  • #5
It could hold a solid object, due to the balancing of three forces -- gravity, friction and the centrifugal force.

The shape of the bent portion matters very much. The vector sum of the centrifugal force and the weight of the body has to be normal to any rotating surface if the object is to keep still wrt the rotating surface without friction. A paraboloid, the surface of revolution of a parabola about its axis, is just such a surface. So, if the wire were bent in the shape of a parabola, a ball placed properly would rest on it. But if it moves just a bit wrt the rotating frame, the coriolis force would shift it out of equilibrium.

A small drop of water, whose dimensions are smaller than the thickness of the wire, will cohere and be carried along the bent portion of the wireif placed properly. But if the volume is more, the drop will tend to push out around the wire due to centrifugal force.
 
  • #6
It won't hold a solid object. What you have there is a blender.

What you are suggesting is that if you spin it fast enough, an object won't be able to fall through. The faster it spins, the less an object will be able to drop before hitting it. But then also, the faster it spins, the larger the force when it does hit.
 
  • #7
Hi Russ,

Before posting a reply, I just wanted to ask you whether your posting is a reply to the general discussion, or to my posting specifically? I have a feeling that what I’ve said could been horribly misunderstood.

After all, it was I who mentioned that it could hold a solid object. The stability of that is exactly the same as keeping an object on a slanted wire on earth. (But theoretically it's possible.) The rest of my writing just describes ordinary mechanics in a rotating frame. Also, in my mind I have no picture of blenders or propellers or the likes.
 
  • #8
Both. It sounds like youa are talking about an object that is rotating with the wire. That would not be a stable situation because the object would have to be balanced on the wire.
 
  • #9
Isn't that what I said? I have mentioned all the points you are talking about.
 

1. Can a wire hanger bowl hold water?

Yes, a wire hanger bowl is capable of holding water. However, the amount of water it can hold may vary depending on the size and shape of the bowl.

2. How much water can a wire hanger bowl hold?

The amount of water a wire hanger bowl can hold will depend on the size and shape of the bowl. Generally, a small wire hanger bowl can hold about 1-2 cups of water, while a larger bowl can hold up to 4-5 cups.

3. Will the wire hanger rust when in contact with water?

Most wire hangers are made of galvanized steel, which is resistant to rust. However, if the hanger is made of a different material such as aluminum or copper, it may rust when in contact with water.

4. How can I make a wire hanger bowl that is watertight?

In order to make a wire hanger bowl that is watertight, you can use pliers to bend and twist the wire hanger into a tight and secure shape. Additionally, you can also use a waterproof sealant or tape to cover any small gaps or holes in the wire.

5. Is a wire hanger bowl suitable for holding hot liquids?

No, a wire hanger bowl is not suitable for holding hot liquids. The wire may not be able to withstand high temperatures and could potentially melt or become deformed, causing the bowl to lose its shape and potentially leak.

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