Why does ice have more friction when it's solid compared to when it's melting?

In summary, Water is made up of loose molecules but a body like ice is bonded strongly into a shape. When free these molecules stick on surface and can be moved by a mere blow of wind but when bonded into a solid body the structure of large collection of molecules put pressure on the molecules below and the actual contact area increases as we increase weight.
  • #1
rudransh verma
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Water is made up of loose molecules but a body like ice is bonded strongly into a shape.
Imagine a ice brick. It will have friction between it and the surface when tried to move. Now it slowly starts melting. The molecules of ice will start sticking on the surface.
Somehow the cluster of molecules opposes the push.

When free these molecules stick on surface and can be moved by a mere blow of wind but when bonded into a solid body the structure of large collection of molecules put pressure on the molecules below and the actual contact area increases as we increase weight. Now the molecules come very close to the surface and this creates inter molecular bonding which opposes any applied force on the body. When we apply force on above part of the body it opposes our push because it’s bonded to the molecules that are in turn weakly bonded to the surface.

In starting the ice is heavy. More actual contact area. More bonding and so more opposing of movement of above part of ice experiencing more friction. As the ice starts melting the pressure of above molecules on the very lower part decrease and so does the inter molecular bonding. This means lesser force on the upper part and the body will move more easily with the lowest layer of molecules in touch with surface.
Am I thinking right on this?
 
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  • #2
Ice is very unusual in that the liquid form is denser than the solid. That's why a melting ice cube slips around. That doesn't happen with other solids.
 
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  • #3
Hornbein said:
Ice is very unusual in that the liquid form is denser than the solid. That's why a melting ice cube slips around. That doesn't happen with other solids.
Let’s just avoid these kind of factors for simplicity. Let’s talk about a general solid body.
 
  • #4
Hornbein said:
Ice is very unusual in that the liquid form is denser than the solid. That's why a melting ice cube slips around.
But the ice block that slides is not floating in the water, so buoyancy or density has nothing to do with it.
If you apply a steady force to ice it may be melted by the pressure. This becomes a lubrication or viscosity issue, rather than a friction problem.
 
  • #5
Baluncore said:
But the ice block that slides is not floating in the water, so buoyancy or density has nothing to do with it.
If you apply a steady force to ice it may be melted by the pressure. This becomes a lubrication or viscosity issue, rather than a friction problem.
This is the reason behind how ice skates work -- the thin blades of the skates exert a downward pressure on the ice, causing it to melt momentarily. The resulting water provides a lubricant that allows the skates and skater to glide along with little friction.

@rudransh verma, if you want to discuss friction, almost any other material than a block of ice would be a better choice.
 
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  • #6
Mark44 said:
@rudransh verma, if you want to discuss friction, almost any other material than a block of ice would be a better choice.
Yeah! Let’s just take a regular solid body in post 1
Baluncore said:
If you apply a steady force to ice it may be melted by the pressure. This becomes a lubrication or viscosity issue, rather than a friction problem.
And to be clear I am applying force horizontal to surface in post 1
 
  • #7
rudransh verma said:
Am I thinking right on this?
It feels like a mish-mash of several different concepts with no clear point/thesis that I can see. For example, usually when someone says "friction" they mean dry friction, but youre talking about melting ice for some reason. What question are you trying to answer?
Yeah! Let’s just take a regular solid body in post 1
All 3 paragraphs in post #1 mention liquid water, so...?
 
  • #8
rudransh verma said:
And to be clear I am applying force horizontal to surface in post 1
As was I for ice. There are bumps and hollows on flat surfaces that must be climbed by a solid body. Ice does not need to do that, it can flow around an obstacle by melting and refreezing. Glaciers bend around corners in valleys.
I think restricting the discussion to solid bodies (without lubrication) would be a good move, but it may be too late for this particular thread.
 
  • #9
russ_watters said:
All 3 paragraphs in post #1 mention liquid water, so...?
Baluncore said:
think restricting the discussion to solid bodies (without lubrication) would be a good move,
Yes. Let’s just eliminate the melted part for the general body and drop this ice discussion. I am not interested in ice but in friction.
 
  • #10
rudransh verma said:
Yes. Let’s just eliminate the melted part for the general body and drop this ice discussion. I am not interested in ice but in friction.
Great. So do you want us to close this thread and you can re-write the OP and start a new one that isn't saturated with liquid water? As far as I can tell, all you're saying now is you have a topic in mind. But you haven't said anything about it yet.
 
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  • #11
russ_watters said:
Great. So do you want us to close this thread and you can re-write the OP and start a new one that isn't saturated with liquid water? As far as I can tell, all you're saying now is you have a topic in mind. But you haven't said anything about it yet.
That would be good.
 
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Related to Why does ice have more friction when it's solid compared to when it's melting?

1. What is friction?

Friction is a force that resists the relative motion between two surfaces that are in contact with each other.

2. What causes friction?

Friction is caused by the microscopic irregularities and bumps on the surfaces of objects that come into contact with each other. These irregularities create resistance and make it difficult for the objects to slide smoothly against each other.

3. How does friction affect motion?

Friction can either slow down or stop the motion of objects. It can also cause objects to heat up due to the energy created by the frictional force.

4. Can friction be beneficial?

Yes, friction can be beneficial in many ways. It helps us walk and grip objects, it allows vehicles to stop and turn, and it also helps to create heat for cooking and warmth.

5. How can we reduce friction?

We can reduce friction by using lubricants such as oil or grease, making surfaces smoother, or by using wheels or rollers to decrease the contact between surfaces.

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