Dream comes true

Sunday 22 July 2012

My last blog post was about an experiment that didn't work, well it's raining outside so I thought I'd return to the lab and try again this time with a better temperature sensor and a more careful technique. The experiment was an attempt to use the heat from my hand to raise the temperature of different masses of water. I kept the area of my hand in contact with the tube constant and stirred with the sensor. last time I use a very cheap digital thermometer, this time I used a vernier temp sensor.

The graph here shows the results from 6 different masses of water from 2.8g to 11.2g. The least steep is the 11.2g trial and the most steep the 2.8g so everything looks like it's supposed to.

I then drew a graph of 1/m vs ΔT/Δt and got a reasonably straight line with a gradient that gave a value of about 0.5W for the heat released by by hand.

I checked out some figures on the internet and found that the totall power released by a body is around 116W. Now the area of a body is about 1.9m2 and the area of the test tube enclosed by my hand was in the region of 12cm2. So if my hand released 0.5W then my whole body should be emitting 790W which is too much. This assumes that the heat is released uniformly from the body, which it isn't. Most heat is released from the unclothed bits.


Tags: heat, IA