Thursday, 23 May 2013

Modelling sweat - cooling effect

Sweating is a way of losing thermal energy to maintain body temperature and prevent overheating.

This experiment will allow you to model how the cooling due to sweating is affected by wind speed and wind temperature.

Equipment

Clamp & stand x 2
Boiling tube
Thin cotton material
Thermometer
Water bath
Stopclock
Hairdrier with cool, warm and hot settings
Small sponge
Water trough
Measuring cylinder

Procedure

Set the water bath to heat water to 37 degrees Celsius.
Attach a layer of the cotton around the boiling tube, either with elastic bands at the top and bottom, or by gluing a sleeve with a small overlap.
Clamp the boiling tube into the stand and add the thermometer.
Clamp the hairdrier on the other stand so that it points at the boiling tube at a distance of 5cm.
With water from the water bath use the sponge to wet the cotton and add 50ml to the boiling tube.
Switch on the hairdrier on it's cool setting and start the stopclock.
Record the temperature on the thermometer after 5 minutes. If the cotton appears to be drying out during this time reapply water with the sponge.

Repeat the experiment increasing the distance between the hairdrier and the boiling tube.
Each time the hairdrier is moved be sure to start with fresh water from the water bath.

To simulate the effect of increased wind temperature repeat the whole experiment using the hairdrier on medium and hot settings.

Safety notes

Take care using electrical appliances around water.
Mop any spills up straight away.