# Frozen Cannonball **URL:** \ **Category:** Factual Questions\ **Created:** [June 1, 2013, 8:40pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887 "2013-06-01T20:40:03Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![DtypeJag](https://avatars.discourse-cdn.com/v4/letter/d/e480ec/32.png) [@DtypeJag](https://boards.straightdope.com/u/DtypeJag)\ **Post date:** [June 1, 2013, 8:40pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/1 "2013-06-01T20:40:03Z")
Will a tightly sealed Cannonball that contains a small amount of water, when frozen, break apart? If so what are the limits to force of expansion of freezing water? ---
**Author:** ![BubbaDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bubbadog/32/333_2.png) [@BubbaDog](https://boards.straightdope.com/u/BubbaDog)\ **Post date:** [June 1, 2013, 9:23pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/2 "2013-06-01T21:23:04Z")
> [@DtypeJag](#): > > Will a tightly sealed Cannonball that contains a small amount of water, when frozen, break apart? If so what are the limits to force of expansion of freezing water? No Next question? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 1, 2013, 9:34pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/3 "2013-06-01T21:34:44Z")
> [@BubbaDog](#): > > Next question? _…what are the limits to force of expansion of freezing water?_ ---
**Author:** ![zoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zoid/32/336_2.png) [@zoid](https://boards.straightdope.com/u/zoid)\ **Post date:** [June 1, 2013, 10:23pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/4 "2013-06-01T22:23:17Z")
> [@Mangetout](#): > > _…what are the limits to force of expansion of freezing water?_ In all fairness that’s a pretty poorly worded question. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [June 1, 2013, 10:26pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/5 "2013-06-01T22:26:17Z")
> [@DtypeJag](#): > > Will a tightly sealed Cannonball that contains a small amount of water, when frozen, break apart? If so what are the limits to force of expansion of freezing water? If the cannonball is nothing but a very thin shell of iron…then maybe. Freezing water will burst a plastic bottle. I’ve never tried to see if it will burst a glass bottle, but if the glass were quite thin, I’m sure it could happen. When you say “a small amount” of water, this tilts the likelihood the other way. It would take something like 98% water, 2% iron shell (by weight) for the expansion of freezing to break through the iron. ---
**Author:** ![zoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zoid/32/336_2.png) [@zoid](https://boards.straightdope.com/u/zoid)\ **Post date:** [June 1, 2013, 10:28pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/6 "2013-06-01T22:28:17Z")
For the force freezing water exerts [you can start here](http://www.newton.dep.anl.gov/askasci/eng99/eng99532.htm), but it’s a bit of a trip down a rabbit hole. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 1, 2013, 10:28pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/7 "2013-06-01T22:28:35Z")
> [@zoid](#): > > In all fairness that’s a pretty poorly worded question. Only grammatically - it’s very clear what the OP wants to know. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 1, 2013, 11:35pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/8 "2013-06-01T23:35:27Z")
I saw pictures of a demonstration once in which a spherical cast-iron bomb, roughly the size of a cannonball and with walls perhaps 3/4" thick, had been filled with water, sealed, and then placed in a pile of dry ice (-110F). After some time had passed, the bomb shattered to pieces. So my answer to the OP’s first question is yes. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [June 2, 2013, 12:23am UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/9 "2013-06-02T00:23:03Z")
> [@Trinopus](#): > > If the cannonball is nothing but a very thin shell of iron…then maybe. Freezing water will burst a plastic bottle. I’ve never tried to see if it will burst a glass bottle, but if the glass were quite thin, I’m sure it could happen. Doesn’t have to be particularly thin either, reports the disgruntled cook who has more than once nearly-filled a sturdy quart mason jar with what she was SURE was a safe level of lovely homemade soup, only to find a frozen shattered mass the next time she opened the freezer. :mad: ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [June 2, 2013, 1:29am UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/10 "2013-06-02T01:29:35Z")
According to the phase diagram of ice, the lowest temperature at which water can remain liquid is about 251 Kelvin, at a pressure of just over 200 megapascals (2000 atmospheres, or over 29,000 pounds per square inch, at about -20 C). So conversely freezing water could exert that much pressure at 20 below C. ---
**Author:** ![thicksantorum](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@thicksantorum](https://boards.straightdope.com/u/thicksantorum)\ **Post date:** [June 2, 2013, 3:24am UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/11 "2013-06-02T03:24:21Z")
Sure. If it’s made of rubber instead of iron. Or, as noted above, a really really thin layer of iron. Or if you just leave it a million years until it’s all rust. ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [June 2, 2013, 4:58am UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/12 "2013-06-02T04:58:39Z")
The capacity of the iron shell to withstand a given force from inside would also be highly variable, depending on many factors, including the temperature that the iron itself had been reduced to by the process of freezing the internal water. Also, the temper of the iron itself, would depend on the casting conditions, how quickly the molten iron was cooled, impurities in the iron, etc. So, while the force of the expanding water can be easily calculated, the resistance of the iron shell cannot be, and that is where the variable lies. ---
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [June 2, 2013, 5:13am UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/13 "2013-06-02T05:13:46Z")
> [@Kimstu](#): > > Doesn’t have to be particularly thin either, reports the disgruntled cook who has more than once nearly-filled a sturdy quart mason jar with what she was SURE was a safe level of lovely homemade soup, only to find a frozen shattered mass the next time she opened the freezer. :mad: You forget that the soup mostly freezes outward, not upward, and that Mason jars are relatively thin. Old milk bottles were much thicker and could constrain the freezing milk better, so you would sometimes get a column of frozen milk rising out of the bottle. I don’t know how or if the rate of freezing affects anything, or if the screw-on cap of your well-sealed Mason jar vs the Pogs that sealed the milk bottles has anything to do with it. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [June 2, 2013, 7:01am UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/14 "2013-06-02T07:01:19Z")
> [@Trinopus](#): > > If the cannonball is nothing but a very thin shell of iron…then maybe. Freezing water will burst a plastic bottle. I’ve never tried to see if it will burst a glass bottle, but if the glass were quite thin, I’m sure it could happen. Freezing water can burst copper pipes. They’re not as strong as a cannonball, but they’re up above plastic and glass. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 2, 2013, 12:47pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/15 "2013-06-02T12:47:13Z")
Freezing water can crack iron pipes also, and engine blocks. ---
**Author:** ![DtypeJag](https://avatars.discourse-cdn.com/v4/letter/d/e480ec/32.png) [@DtypeJag](https://boards.straightdope.com/u/DtypeJag)\ **Post date:** [June 2, 2013, 6:16pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/16 "2013-06-02T18:16:27Z")
I should have made my question clearer. I am assuming a more or less “normal” cannonball. 4" to say 8" dia solid cast iron except for a hollow core say 25% of diameter. Tripolar reminded us that a frozen engine block can crack but the cast iron there is a minimum of maybe 1/4". Lumpy said that from the phase diagram of water that the force could be around 29,000 lbs/sq in. That is somewhat above the tensile strength of cast iron but below most steels. Question answered maybe? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 2, 2013, 8:30pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/17 "2013-06-02T20:30:57Z")
I’m not sure about the tensile strength of cast iron being effective here. Cast iron is notoriously brittle due to it’s high carbon content, and if I understand it correctly, cannon balls are made from very low grade iron to reduce costs. Given a perfectly spherical cast iron cannon ball with a perfectly sperical hollow core for the water maybe the brittleness of cast iron wouldn’t come into play, but cast iron certainly doesn’t have the ductile quality of steel that would allow it to deform before breaking. ETA: Cast iron engine blocks are definitely made from from either actual steel, or an iron alloy with much greater strength than the iron cannonballs would be made from. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 2, 2013, 8:36pm UTC](https://boards.straightdope.com/t/frozen-cannonball/659887/18 "2013-06-02T20:36:46Z")
> [@DtypeJag](#): > > I should have made my question clearer. I am assuming a more or less “normal” cannonball. 4" to say 8" dia solid cast iron except for a hollow core say 25% of diameter. Tripolar reminded us that a frozen engine block can crack but the cast iron there is a minimum of maybe 1/4". Lumpy said that from the phase diagram of water that the force could be around 29,000 lbs/sq in. That is somewhat above the tensile strength of cast iron but below most steels. Question answered maybe? You could use the equations for a [thick-walled pressure vessel](https://en.wikipedia.org/wiki/Cylinder_stress#Thick-walled_vessels) to calculate the stresses. The two equations there have constants that you can figure out from your particular situation. In this case, radial stress is maximum at the inner surface (29,000 psi), and zero at the outer surface. Now you can solve for constants A and B, plug them into the equation for tangential stress, and then evaluate that to see whether the tangential stress exceeds the yield stress for the material anywhere in the cannonball.