# Thermal help pls

1. Apr 3, 2004

### math4me

My son is studying science at the moment, and i was wondering if anyone would be kind enough to answer a few question:

1. Why does sugar increase the temperature of water?

2. Why does a fan blowing on heated water cool down faster?

and 3. How does insulation keep water warm?

Thankyou much appreciated.

2. Apr 3, 2004

### Integral

Staff Emeritus
Perhaps you mean, sugar increases the boiling point of water. The heavy molecules of sugar require more energy to speed up. There may also be effects on the surface tension. Hopefully someone else will have a more detailed answer for you.
The main mechanism for heat transfer in air is convection. The moving air ensures that there is always a cool layer next to the surface of the water. If the air is not moving the layer of air next to the water will warm to the same temperature as the water, thus serving as an insulating layer. Remember that there must be a temperature differential to get heat flow. The moving air maximizes the temperature differential at the surface of the water.
and
Insulation is a layer of material with a low THERMAL CONDUCTIVITY this means that the material conducts a small amount of heat across a difference in temperature. The inner layer of the insulation will be at the temperature of the contents of the container, the outer layer will be at the environmental temperature, the amount of heat lost from the contents is determined by the ability of the insulating material to carry heat. Still air is a very poor conductor of heat thus is an excellent insulator. This is why we now have windows with 2 panes of glass, the inner region is still air very little heat is transfered across.
I hope this is of some help.