pls. explain?

Question

an ice cube floats in a glass of water. the ice cube contains many air bubbles. when the ice melts, will the water level in the glass rise, fall, or remain unchanged?

Answer 1

The reason ice floats is not because of air bubbles. It floats because it is less dense than very cold water. Any object floating in water displaces a volume of water with a mass equal to that of the object. As the ice melts, its density will equal that of the surrounding water. The volume will then equal the volume of water previously displaced. The level of the surrounding water will not change. Taking air bubbles into account, the level would fall by the equivalent of the mass of trapped air. This will be extremely small and unlikely to be measurable using instruments outside a laboratory.

Answer 2

Kon-nichi-wa Ishiru!
Yes, it was Archimedes; and he told me when we were swimming in a pool (joke!) that his body loses in weight by as much as volume-of-his-body specific-weight-of-water.
As the ice is lighter than water (because specific-weight-of-ice is less than that of water), then a
certain volume of the ice cube V should be under the surface and the rest of cube should be above. Ice cube would have the same weight after melting as before and would occupy now the volume V. Thus water level would not change. The effect of bubbles is negligible as specific-weight-of-air is 1500 times less than that of water. Understood? Sayonara!

Answer 3

This is the classical Archimedes principle (c. 287 BC – 212 BC) was an ancient Greek mathematician, physicist, engineer, astronomer, and philosopher. He is reputed to have said, "Eureka!" when he discovered it in the bathtub...

A description of what happens when something floats on water, or sinks into water, is in Wikipedia:
http://en.wikipedia.org/wiki/Buoyancy

Hope this helps!