Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.

#
What is the mass of a yardstick?

The goal of this exercise is for your group to predict
the mass of a yardstick.
If the actual mass lies within your predicted range,
you win!

It may sound easy, but here's the problem:
you are not allowed to examine or touch the yardstick in question
before making the prediction.
Instead, you have access to the following:

- five pieces of a broken yardstick
(which do not add up to an entire yard)
- a triple-beam balance scale
- a ruler
- some graph paper
- the knowledge that an intact yardstick
is one yard long

To start, please fetch a triple-beam balance scale
for your group.
Use it to measure the shortest piece of wood in your set.
Then have one group member walk up to the board at
the front of the room and write down your measurement.
We'll talk about using the balance briefly,
and discuss the measurements made by each group.

Then, you are on your own. Good luck!

Hint: if you can figure out the **linear mass density **
of a yardstick (that is, the mass per millimeter or
centimeter), then you can
compute the mass of any given length.

Hint^{2}: if you know the **uncertainty** in the
linear mass density, then you can compute
the uncertainty in the mass of any given length.

Hint^{3}: it might help to take a look
at the graph below. Click on it to see a larger
version.

####
You must hand in ....

Each group of three students must submit

- good graphs,
** one from each student**

plus the following,
just one per group:
- a neat table of all measurements
- a page which shows one example of each type of calculation
(but not all the calculations)
- the predicted mass (with uncertainty)
and actual mass (with uncertainty)
- a sentence or two explaining the results --
did the predicted mass agree with the actual mass
to within the predicted uncertainty?
- your guess at the largest single source of error
in the experiment, and how it could be reduced next time

Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.