How Can You Measure Outdoor Temperature Using Only Wood Blocks and Tape?

[persian52]

Homework Statement

Design an experiment to determine the temperature outside.

Materials:
2 blocks of wood
stop watch
Measuring tape

The Attempt at a Solution

I believe it has something to do with measuring the rate of flow of a viscous liquid down a ramp.
The colder the temperature, the less distance per second the fluid travels.
Once baselines are established at known temperatures, it would be a fairly reliable instrument.


BUT

the thing is we can't use any type of liquid!
we have to do it with all the materials we have and nothing else...

 

[Pythagorean]

my first impulse is to say thermal expansion, but I don't know what you'd need the stopwatch for. You could just leave one block outside and one inside for a really long time, but you'd also have to know the temp inside for this to work:

http://en.wikipedia.org/wiki/Thermal_expansion

But then, you're title has nothing to do with thermal expansion.

 

[persian52]

my first impulse is to say thermal expansion, but I don't know what you'd need the stopwatch for. You could just leave one block outside and one inside for a really long time, but you'd also have to know the temp inside for this to work:

http://en.wikipedia.org/wiki/Thermal_expansion

But then, you're title has nothing to do with thermal expansion.

i got ur point, true

 

[jtebb]

Not sure if anyone cares, but to measure the temperature outside with this equipment, one could determine the speed of sound, which varies with temperature according to v=332m/s + 0.59T, where T is the temperature in degrees celsius.

Using the equipment, clap the boards about 200m from a wall, and measure the time taken for the echo to return (a trip of 400m). To make more accurate measurements, set up a rhythm of clap-echo-clap-echo and measure multiple trips. The averaging will minimize start and finish reaction time delays. Counting 20 round trips for example, that's 20x400m = 8000m in whatever time is measured with the stopwatch. v=d/t will give you the speed of sound on that day. Then use the speed of sound equation and solve for T, the temperature.

Cheers!