  Question about friction and sink plungers   

  Normal Modes I  Onepage summary 

   example of superposition  

   examples of systems with 2 degrees of freedom 

  The three big messages of normal modes 

  Example 1  find equation of motion 

   solution 

   Proof of idea 1: Eigenvectors correspond to normal modes  

   Example 2  find eigenvectors too 

    discuss eigenvectors 
