Problem 78

This is not my favorite problem in the book, but it does have my favorite answer. The “round number” given in the back of the book is, of course, zero. A floating body displaces its weight of water; that is, it displaces a volume of water equal in weight to itself. In this case, the floating body is ice, so when it melts its new volume is equal to the volume of water it was displacing. So no change in water level.

You may have heard, in discussions of global warming, about the threat of ice melting at the poles and raising sea levels. Doesn’t that contradict what we’ve just learned? No, it doesn’t. The ice that may raise sea levels if it melts is ice that is currently perched on land masses—it isn’t the floating ice. Most (all?) climatologists are careful to make the distinction, but sometimes their words get “simplified” when repeated by others.

Problem 79Problem 77

Last modified: January 22, 2009 at 8:32 PM.

Den Hartog’s Mechanics

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Problem 78