why do objects float or sink in water ?

 

Floating and Sinking : why do objects float or sink 

in water ?

Objects are made up of extremely small molecules. Molecules can be packed closely together, 

as in a rock, or spread out, as in bubble wrap. The density of an object is affected by the 

positioning of molecules. Objects with tightly packed molecules are denser than those with 

loosely packed molecules.

Density affects why some things float and others sink. Objects that are denser than water sink, 

while those that are less dense float.

For Example: 

1. Compare the mass of the wax to the mass of an equal volume of water.

2. since you are comparing the same volume, the one that has more mass must be more dense.

3. The one with less mass must be less dense.

4. Since the wax is less dense than water, the wax float in the water.

Wax and Water (Molecular Level)

WAX	WATER
Made of Hydrogen and Carbon atom	Made of Hydrogen and Oxygen atom
Molecules are long and intertwined	Molecules are very close together
They are light	They are heavier due to oxygen presence. Oxygen is heavier and little smaller than carbon

Summary (Basic Concept):

1. The density of an object determines whether it will float or sink in another substance. 

2. An object will float if it is less dense than the liquid it is placed in. 

3. An object will sink if it is more dense than the liquid it is placed in.