Assignment: Units Name:

Assignment: Units
1. Which of the following best describes the length of the beetle's body in the picture to the left?
 Between 0 and 2 in
 Between 1 and 2 in
 Between 1.5 and 1.6 in
 Between 1.54 and 1.56 in
 Between 1.546 and 1.547 in
2. Describe your reasoning for answer #1. (Explain
your answer clearly and concisely using
terminology that you learned in this unit.
Try measuring the diameter of a tennis ball using the meter stick.
3. What is the uncertainty in this measurement?
4. What factors limit your ability to determine the
diameter of the ball?
5. What is a more realistic estimate of the uncertainty in your measurement of the diameter of the
6. Explain how you would try to determine the thickness of a CD case from this picture.
7. How can you get the most precise measurement of the thickness of a single CD case from this
picture? (Even though the ruler is blurry, you can determine the thickness of a single case to
within less than 0.1 cm.)
8. Use the method you just described to determine the thickness of a single case (and the
uncertainty in that measurement)
9. What implicit assumption(s) are you making about the CD cases?
10. The foot has long been a unit of measurement, but it has ranged between 10 and 27 inches.
Today it is standardized at 12”. Describe why the standardization of this measurement is so
important and why you think 12” might have been selected. (This is less about a ‘historically
correct’ answer and more about effectively reasoning your answer.)
11. Assume that you’ve been given the following question to solve:
What is the average height of all the children 11 years old in the world today?
Unless you measure every child in the world today and average the number, this question can’t
be solved precisely. But it is possible to come up with a reasonable solution to the question.
A. In a series of scientifically considered steps below, determine how you would come up
with the best possible accurate solution to this question.
B. Give a sample of the types of equations you would use to solve this problem.
C. Explain what sort of margins of error would occur in your solution.