AP Physics 2 : Kinetic Molecular Theory
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Example Questions
Example Question #1 : Kinetic Molecular Theory
What is the average molecular kinetic energy of a gas at a temperature of 
We know that the expression for average kinetic energy is:
Where average velocity of a gas is:
Plugging this into our expression for kinetic energy, we get:
Plugging in our values, we get:
Example Question #2 : Kinetic Molecular Theory
A mixture of methane 
For gases at equal temperatures, we know that they both have the same average kinetic energy:
Note that 
Then taking the square root of each side:
Now all we need is the molecular weight of each molecule:
Plugging these in, we get:
Example Question #3 : Kinetic Molecular Theory
What is the ratio of the rate of effusion of carbon dioxide 
We can use Graham's law to solve this problem, which states that the ratio of effusion between to gasses is the square root of the inverse of the gases' molecular masses:
Therefore, in this problem we get:
Now we just need to determine the molecular masses of the two gasses, starting with carbon dioxide:
Plugging these in:
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