[Physics] Fastest way to melt ice cubes in glass of water

aireveryday-lifeicethermal conductivitywater

I'm in a restaurant and order a glass of water. What I get is about 50% water 50% ice cubes.
So, after finishing my water, I'm left with half a glass of ice cubes. I'm in a hurry, so need to leave as soon as possible, but I do not want to waste half a glass of (potential) water, so I want the ice to melt as quickly as possible.

What can I do to get the ice cubes to melt as quickly as possible?

The two most promising options that I can think of are:

  1. Leave enough liquid (i.e. water) in the glass so that the ice cubes are fully submerged.
    Here the water around the ice would be about 0°C, but water conducts heat rather well.
  2. Periodically drink the molten ice so that the ice cubes are not submerged, but instead surrounded by air. Here I could regularly blow into the glass and therefore have an air temperature of about 25-30°C around the ice cubes. Air doesn't conduct heat very well, so this might in fact be slower.

For additional melting speed I could also hold the glass in my hands.

So what is the fastest way to melt the ice cubes?

Best Answer

  1. Leave some water to cover them and hold the glass in your hands or between your legs (careful though, if you choose the second option you will probably end up with wet trousers). Your body temperature is around $36$ °C, so with some patience you should be able to melt all the ice. It is better to leave some water because air is a really poor heat conductor.

  2. If keeping them inside the glass is not required, then there is an even faster way: put them directly in your mouth, one by one (or even all together if you like). This way every side of the cube will be in contact with a surface at $36$ °C, and the melting will be even faster. You can also hold them in your hands: this will melt them quickly for sure, but you will probably lose all the water.

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