Icebergs

[tock24]

Question came up in our 'friendly' championship quiz last night....

How much of an iceberg is above water level? Is it one third, one seventh or one eleventh?

My school geography always said one eighth, so that didnt help!

Thanks in anticipation....

[kempie]

Icebergs float because the density of ice (around 900 kg per cubic meter) is lower than that of seawater (around 1025 kg per cubic meter). The ratio of these densities tells us that approximately 12% (~1/8) of the iceberg's mass must be above water.

[peskie]

a survey of the office has shown different responses according to different age groups the 50's say one eighth, the 40's say one ninth and the 30's say one tenth. Given the options available perhaps it is now one eleventh?? Another whizz explained that the level of salt in sea water is actually reducing, which would explain why the answer is constantly changing? Anyone got any other suggestions??

[gen2]

Pure ice floats in water with about one eleventh visible.  In the real world though, icebergs are white because of trapped air inside them.  That air makes them more buoyant so more of the iceberg will be visible above the water and less below.  The amount of trapped air depends on the origin of the ice and what pressure it has been subjected to, so there is not any one correct answer to the question.  Different icebergs will float higher or lower.  From the choices given, I would say that icebergs show between one seventh and one eleventh above water.  That also explains the range of answers given by peskie - so everyone is right.