A cold pack, applied to reduce swelling, is more effective if it contains melting ice at 0 °C rather than water at 0 °C. Why is this?

D: The heat that transfers from the bruised part is used to break the bonds between adjacent water molecules to melt the ice, rather than to increase the kinetic energy of the molecules. Temp measures the average kinetic energy of the molecules. Hence temperature does not rise until all the ice has melted.