thermodynamics - How fast do molecules move in objects?

I guess it depends on the heat or the type of the material but can you give some examples or formulas to calculate it ?

The best example would be the average speed of the air molecules (all types in the air) at room temperature or water molecules at human body temperature.

Answer

It depends on the mass of the molecule in question. Here's a quick, back-of-the-envelope answer. In a body at thermal equilibrium, every energy mode has the same average amount of energy, $\frac12kT$, where $T$ is temperature and $k$ is Boltzmann's constant. One of the energy modes is the translational kinetic energy of a molecule in some direction $x$, $\frac12mv_x^2$. We can solve

$$\frac12kT=\frac12mv_x^2$$

to find

$$v_x=\sqrt{\frac{kT}m}$$

and then plug in $k=1.38×10^{-23}\rm{m^2 kg s^{-2} K^{-1}}$, $T=300\rm{K}$, and for $m_{\rm{N}_2}=2×14\rm{u}=2×14×1.66×10^{−27} \rm{kg}=4.65×10^{−26} \rm{kg}$ to get

$$v_x=298\rm{m/s}=667mph.$$

The molecule is also moving in the $y$ and $z$ axes, so the answer depends on what exactly you mean by average speed: mean spead vs. root-mean-square speed.

This ignores rotational and vibrational degrees of freedom. Similar calculations may be performed for other substances.

Some links: http://en.wikipedia.org/wiki/Root-mean-square_speed