MODEL: The average density of the rock is its mass divided by its volume (equation 13.1).
SETUP: We'll need to express the total mass M in terms of the mass of basalt and the mass of air. Express both in terms of the unknown fractionfair of the rock's volume that is occupied by the bubbles. SOLVE: Set your expression for the rock's density equal to the density of pumice computed from its given total mass of 10 kg and total volume.

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© 1998 Susan M. Lea