Cooling off with thermal conductivity | Hey Ray

When it is hot, everyone looks for creative ways to keep cool.

One way to cool off is to give your heat to other things!  

We have shown you in the past that in thermodynamics, the branch of science that deals with the flow of heat, energy, and work of a system, heat always travels from hot to cold.  

This means hot things lose heat to colder things.

If you go into a kitchen with granite countertops and a wooden cutting board, you will notice that the granite countertops feel colder than the cutting board. 

This is just a feeling because they are both at the same temperature if they are not getting heat from something else.  

Granite feels colder because granite has better conductivity than wood. Conductivity is a material's ability to transmit heat or energy.  We are talking about heat today, and granite is able to better conduct heat than wood. 

This means heat is flowing from your hand into the granite. Your body perceives this as the granite being cooler, but it is just heat leaving your body.

Dogs seem to know this idea better than us.  

Many people find that their dogs like to lie on tile floors when it is hot.  This allows them to cool off by giving their heat to the tiles on the floor.  As long as you can find something with good thermal conductivity that is colder than your body temperature, you can lend it some of your heat.