title: problem 'Tkinter as tk' imported but unused
body: <p>read the related questions but I did not understand much, I could say that nothing, I'm aware I'm in a mechanics course at the university, and I have to use a python code for a certain calculation, the thing that throws me problems but execute but I am intrigued by the error that points, and I searched as a resolution but I do not get the solution so I found this forum and I hope to get to it, the code is as follows:</p>
  
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  <p><a href="https://i.stack.imgur.com/m784r.png" rel="nofollow noreferrer">imagen 2</a></p>
  
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  <p><a href="https://i.stack.imgur.com/v0fZq.png" rel="nofollow noreferrer">imagen 5</a></p>
  
  <p><a href="https://www.mediafire.com/file/uvuyc2v822i3h9b/atwood_viscous_fluid_solver.py/file" rel="nofollow noreferrer">https://www.mediafire.com/file/uvuyc2v822i3h9b/atwood_viscous_fluid_solver.py/file</a></p>
  
  <p>I would appreciate it if you can help me, and that the translator helps you enough.</p>