Preflight assignment 7


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  1. (Re)read Example 4.7 in Taylor. For me, the trickiest part was understanding the little step of geometry just before Eq 4.59, where Taylor says "the length BC... is r theta" Look at the picture, convince yourself you understand! (If you don't, just say so in the space below. If you do - was it so obvious you didn't even have to think, or did it take a moment of head-scratching?)


  2. Look at the figure below, which shows a possible design for a child's toy. The designer wants to build a "weeble" (which wobbles, but doesn't fall down :-) It is a single, solid object, the shape is a perfect hemisphere (radius a) on the bottom, glued to a solid cylinder on top. The CM is shown, it is "h" above the base. (You don't need to compute it - it's given)
    Come up with a formula for the gravitational potential energy U(theta) when the whole toy is tipped to an angle theta. (Sorry, but you will need to pull out a paper and pencil if you want to get this right! It is not identical to Taylor's example above) Fill in your answer for U(theta) in the space below the figure.

    image


    (Note: on an upcoming homework, you will finish this problem, and thus decide what the criterion is on h and a to make this toy stable)
  3. The above situation sure looks like a 3-D object, yet we are in Taylor's chapter called "one-dimensional systems". Why do we consider this a 1-D problem?



  4. Please submit a question you have about the reading assigned for the upcoming class. What seemed hard, was something confusing, what would you like us to spend class time on? If you can't come up with any question, how about a comment - (did anything strike you as interesting? )
    Reminder: the reading assignments are on our course calendar


    Thanks for your time.

Optional! - below is a space for any additional relevant comments, thoughts, or suggestions you have.




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