Water level before and after metling of ice cube

[wei1006]

Homework Statement

A big ice cube is placed in a small glass of water. The level of water in the glass is marked. When the ice cube melts completely,the overall water level will remain the same. Explain.

Homework Equations

Upthrust= weight of fluid displaced

The Attempt at a Solution

Since the ice floats,weight of fluid displaced is equal to the weight of ice itself. Since upthrust equals to weight of fluid displaced, it is equals to density of ice times volume of ice times gravitational force times area. Since the volume of ice is unchanged before and after melting, the water level remains the same.

 

[FactChecker]

Since the volume of ice is unchanged before and after melting, the water level remains the same.

This is not true. Water takes more volume in the ice form than in the liquid form.

 

[wei1006]

This is not true. Water takes more volume in the ice form than in the liquid form.

May I know why is the water level the same then?

 

[FactChecker]

May I know why is the water level the same then?

I can't answer a homework problem for you. Review the basic facts about ice floating in water and you will find the answer.

Maybe you are using the term "volume" wrong. In your solution, you refer to both volume and area.

 

[haruspex]

May I know why is the water level the same then?

You made a good start:

Since the ice floats,weight of fluid displaced is equal to the weight of ice itself.

What about when it has melted?