The fact that desert sand is very hot in the day and very cold at night
is evidence that sand has a
low specific heat or
high specific heat.
Suppose we compress some gas, holding the pressure of the gas constant.
Does the internal energy of the gas
increase,
decrease, or
remain the same?
Consider a block sliding across the floor and finally coming to rest
because of friction between the block and floor. This process is
reversible or
irreversible.
According to the second law of thermodynamics, the net entropy can never
increase or
decrease.
When we compress a gas quickly, the gas gets hot. For example, this happens
when we use a pump to inflate a bicycle tire. Feel the pump with your hand,
and you will find that it's warm after you have pumped up the tire.
Why does a gas get warm when you compress it?