Introduction:
Ice and water both have the same temperature at 0 degrees Celsius, but ice is more effective in cooling compared to water at the same temperature. This can be explained by considering the physical properties and the process of heat transfer.

1. Latent Heat of Fusion:
Ice has a higher latent heat of fusion compared to water. Latent heat of fusion is the amount of heat energy required to convert a substance from solid to liquid state without changing its temperature. For ice, this value is 334 kJ/kg, while for water it is only 0.334 kJ/kg. This means that ice requires a significantly higher amount of heat energy to melt compared to water.

2. Heat Absorption:
When ice is at 0 degrees Celsius, it absorbs heat from the surroundings in order to melt and reach its melting point. This heat absorption process cools down the surroundings. On the other hand, water at 0 degrees Celsius does not require any heat absorption to maintain its state, so it does not actively cool the surroundings.

3. Heat Transfer:
Heat transfer occurs in three main ways: conduction, convection, and radiation. When it comes to cooling, conduction and convection are the most relevant.

- Conduction: Ice is a solid and has a lower thermal conductivity compared to liquid water. This means that it is less efficient in transferring heat through conduction. Therefore, when ice is in contact with a warmer object, it transfers heat at a slower rate compared to water, resulting in a slower cooling process.
- Convection: Ice has a lower density compared to water. This means that when ice is in contact with a warmer fluid, it tends to float and form a layer between the fluid and the object being cooled. This layer of ice acts as an insulator, reducing the rate of heat transfer between the fluid and the object. In contrast, water has a higher density and better convection properties, allowing it to transfer heat more efficiently.

Conclusion:
In summary, ice at 0 degrees Celsius is more effective in cooling than water at the same temperature due to its higher latent heat of fusion, heat absorption during the melting process, and slower heat transfer through conduction and convection. These factors combined make ice a better choice for cooling applications where temperature control is crucial.

ice is more efficient than water at 0C because ice can sustain energy by converting it into latent heat of fusion for conversion into liquid whereas water is already in the form of liquid.