Sweating and heat loss
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Sweating and heat loss (Adhal Mahmood) Aim To find out whether heat is lost faster over a sweaty body compared to a dry body. Apparatus 2 Boiling tubes 47ml max 2 Measuring jug 50ml max A Beaker 250ml max 2 thermometers Paper towels A kettle to boil water A stopwatch 2 magnifying glasses (8x) 2 corks with a small hole through the centre A test tube rack Preliminary work In my preliminary work, I need to find out how much water to use, whether the tissue should be wet with hot/cold water, how often the readings should be taken, how accurate should the readings be, how many readings should be taken and what my starting temperature should be. My results are as follows. Starting temperature of 40°c Time (secs) Wet towel (°c) Dry towel (°c) 30 36 38.9 60 35 38.5 90 34 37.9 120 33.9 37.5 150 33 37 180 32.6 36.9 210 32.3 36.8 240 31 36.5 270 30.4 36 300 30.3 35.9 Starting temperature of 65°c Time (secs) Wet towel (°c) Dry towel (°c) 30 51.1 53 60 48.2 51.9 90 46.4 51 120 46 50 150 44.3 49 180 42.9 48.4 210 42.6 46.9 240 41.7 48 270 40.2 47.5 300 39.3 47 Starting temperature of 60°c Time (secs)
I will keep everything else the same throughout the experiment so that I can obtain reliable results. If I don't keep the starting temperature the same, then in one of the experiments there will be a larger gradient for the water to cool down in and so this will make my results void. If I don't keep the amount of water in each tube the same then in one experiment the cooling down process will be longer than the other and will also make my results void. If I don't keep the size of the test tubes the same then in one experiment there may be more surface area of water exposed than in another, so one of the experiments will cool down faster then the other. This would make my results void. If I don't keep the material of the bungs the same, then in one experiment I may have a rubber bung and in a different experiment I may have a cork. The rubber bung is a much better insulator and so this will let less heat out than the cork. This will make my results void.
Also when I looked at the stopwatch every 30 secs, I sometimes took a reading too early or too late. This did not reflect on my results because my graph had a smooth curve, but to avoid doing this again, I would have one person reading the timer and another person getting ready to take the reading. By doing this, I would be working more efficiently. I have one anomalous result on my experiment. On the graph showing a dry body, the very last result which was taken at 600 secs is anomalous. This is due to either taking the reading too late therefore letting the water to cool down more than it is allowed to. Or it is due a fault when taking the reading e.g. taking the reading at a much lower reading than it actually is. I could prove that this is an anomalous result by repeating the experiment. If I did this then there would be no anomalous results because I would be more accurate when taking readings and timing. Critically Evaluate Evidence A better way to have done it would have been to concentrate on the accuracy of timing and results. If I were to do my experiment again I would alter the frequency of results. This would also give the same conclusion.
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