CATAGORY: Mechanics
 QUESTION: At room temperature, an oxygen molecule, with mass 5.31 x 10-26
kg, typically has a KE of about 6.21 x 10-21 J. How fast is it moving?

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We will make the simplifying assumption here that all of the KE is in
translational kinetic energy and not rotational energy.  This gives us

(1)   KE = 6.21 x 10-21 J 

or

(2)    1         
       - m v^2 = 6.21 x 10-21 J  
       2         
        
Where m is the mass of the molecule and v is its velocity.
Solving for v

(3) v = sqrt( 2 x 6.21 x 10-21 J / m )

      = sqrt( 2 x 6.21 x 10-21 J / 5.31 x 10-26 kg )
      
      = 484 m/s
      
      ***************
      *             *
      * v = 484 m/s *
      *             *
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