#
Standing waves on a string experiment (part 1)

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Using elastic cord ....

First, measure some properties of the elastic cord.
You'll need to include uncertainties in just about every quantity.

* First, make all these measurements. *

- Cut a piece of stretchy cord roughly 170 cm long.
Measure the length
**L**_{tot} and mass **m** of this cord
carefully. Include uncertainties in each quantity.
- Place the cord onto the table, under no tension but aligned as
straight as you can make it.
Place two marks onto the cord, separated by about
**50 cm**.
Measure the distance between these marks, **L**_{1},
and its uncertainty.
- Hang a mass of
**M = 650 g** by the cord over the pulley.
Once again, measure the distance between the two marks,
including an uncertainty. Call this **L**_{2}.
* Next, do some calculations. *

- Compute the linear mass density
**μ** (kg/m) of the cord.
Include an uncertainty.
- Compute the linear mass density
**μ**_{s}
of your cord when it is stretched and holding 650 g.
Include an uncertainty.

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Preparing for the next class

- Arrange for one student to take your piece of stretchy cord
away at the end of class;
you will need to bring it back to use next time.

- Compute the speed
of waves travelling down the stretched cord,
and an uncertainty in that speed.