Measurement Activity

Grandma Lewin's Hypothesis

View MIT Physics 8.01 Lecture 1 from 4:50 - 11:11 (available on ITunes U and MIT Open CourseWare) and then discuss the following questions. For your convenience, Prof. Lewin's measurements are reproduced below.

Aluminum rod length: Al rod lengths

Person's height: person's height


  1. Prof. Lewin asserts that the "accuracy" of his measurements was +/- 0.1 cm. What was his justification for this?
  2. Does Prof. Lewin's use the term "accuracy" in the same way we use it? If not, what term do we use instead, and what do we mean by "accuracy?"
  3. Could Prof. Lewin reasonably justify claiming an uncertainty less than +/- 0.1 cm? Why or why not?
  4. What is the purpose of measuring the aluminum rod in Prof. Lewin's experiment? Did measuring the aluminum rod accomplish its purpose? Why or why not?
  5. How did Prof. Lewin arrive at the uncertainty 0.2 cm in his result (as shown below)?
  6. Did Prof. Lewin's result confirm or cast doubt on his grandmother's hypothesis? Justify your answer.
  7. Prof. Lewin remarked:

    "I want you to appreciate that the accuracy of 1 mm was more than sufficient to make the case. If the accuracy of my measurement had been much less this measurement would not have been convincing at all."

    What did he mean by this statement? Give an example to justify your answer.
  8. Are you convinced of the validity of Prof. Lewin's result? Why or why not?

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last update March 27, 2008 by JL Stanbrough