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

[rudransh verma]

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?

 

[Hornbein]

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.

 

[rudransh verma]

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.

 

[Baluncore]

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.

 

[Mark44]

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.

 

[rudransh verma]

@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

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

 

[russ_watters]

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...?

 

[Baluncore]

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.

 

[rudransh verma]

All 3 paragraphs in post #1 mention liquid water, so...?

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.

 

[russ_watters]

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.

 

[rudransh verma]

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.

 

[Mark44]

Thread closed.
@rudransh verma, go ahead and start a new thread.