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Question
Molecules in air in the atmosphere are attracted by gravitational force of the earth. Explain why all of them do not fall into the earth just like an apple falling from a tree.
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Solution
Air molecules in the atmosphere are attracted by the gravitational force of the earth but they do not fall into the earth due to the reason that the molecules in air have some random motion due to temperature, so their resultant motion is not exactly the vertically downward direction.
But in the case of apples, only vertical motion dominates because of being heavier than air molecules. But due to gravity, the density of air is more near to the earth than the density as we go up.
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