A block of wood has specific gravity 0.80.When placed in water,what percent of the volume of the wood is above the surface?
A)0,the block sinks.
B)20%
C)80%
D)50%
E)100%

Question

Quizplus · Accepted Answer

Specific gravity is the ratio of the density of the object to the density of water. Here, specific gravity of the block of wood is given as 0.80. This means that the density of the block of wood is 0.80 times the density of water.
When an object is placed in water, it displaces a volume of water equal to its own volume. If the displaced volume of water is more than the volume of the object, the object floats, and if it is less than the volume of the object, the object sinks.
Since the block of wood has a lower density than water, it displaces a volume of water that is greater than its own volume. Therefore, the block of wood floats. The percent of the volume of the wood above the surface is equal to the fraction of the volume of the block that is above the waterline. This fraction is equal to the ratio of the density of air to the density of water, which is approximately 0.20 or 20%.

A Block of Wood Has Specific Gravity 0