Ice Cubes Cracking
Name: Laura L.
Why do ice cubes make a cracking sound when put in water or soda or some kind of
When ice cubes freeze air is trapped inside. That is what makes ice cubes in your refrigerator
look hazy. When you drop an ice cube into warm soda or water, the ice cube warms up faster
than it can melt, so that the trapped air expands inside the melting cube. This increase in
the internal pressure causes the ice cube to crack and that is the sound you hear.
What is actually happening is known as thermal stress. When you pour warm water or soda over a
cold ice cube, the difference in temperature causes problems for the ice cube. The outside of
ice cube starts to warm up (pay little attention to the melting at this point), but the inside
is still rather cold. All materials have a property know as the coefficient of thermal
expansion which is a function of how much something will lengthen if it grows in temperature.
In other words, as the temperature gets higher, the crystals on the outside of the ice want
to expand or lengthen, but the crystals still in the middle do not see this new temperature
yet, and they do not want to expand. These two different layers of the outside wanting to
grow and the inside not wanting to grow create stress in the ice cube. The ice cube can
only take so much of this stress until it breaks. The cracking you hear is the ice cube
breaking to relieve this stress.
Thanks for using NEWTON.
Associate Mechanical Engineer
The soda is warmer than the ice. In general, things expand when heated. The warmer soda causes
the outside of the ice to expand a little too fast to stay together, Thus, the cubes
sometimes crack -- that is the sound you are hearing.
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Update: June 2012