Re: Is skin a solid, or is it a liquid because it is the shape of its container? Is fire a gas?

Subject: Is skin a solid, or is it a liquid because it is the shape of 
its container? Is fire a gas?


Hello Claudia,

It looks like you were doing some scientific thinking!  You were probably 
told that one definition of a liquid is that it will assume the shape of 
the container that it is in.  However, that is not the most complete way 
to define liquid.  Let's consider your skin.  It does seem to fit the 
container (your body) very well.  But, think about this- If you could 
step out of your skin, pick it up and place it inside another container- 
like a bucket, would the skin assume the shape of this container?  The 
answer is 'no'.  It might seem to get close, but because skin is a SOLID, 
it would not flow into the exact shape of the container.  So, the fact 
that skin assumes the shape of your body is not enough of a description 
to define skin as a liquid. 

A slightly different definition of liquid is that is has definite volume, 
but does NOT have definite shape.  In our gruesome example above, we 
would see that skin DOES have a definite shape (by not conforming to the 
shape of the bucket), and is therefore not a liquid.  

Your last question,"Is fire a gas?":  The answer is "yes" and "no"!  
Fire, itself is the release of energy due to the burning of a fuel. In 
that definition, fire itself is not a gas. However, fire will only occur 
when the fuel IS a gas, or is turned into a gas.  For example, wood (a 
solid) will burn and produce fire, but only when it is heated enough for 
the fuel inside to boil off into a gas.  When this gas mixes with oxygen 
in the air (another gas) it can then burn and release energy in the form 
of 'fire'.

Therefore fire should be thought of, not as a gas, but it is the result 
of when gases burn. Fire releases energy in the form of heat and light.

I hope that this helps you. I know it is a bit confusing!

Mad Scientist,
Jay Shapiro