# If I touch an object, am I touching the atoms on its surface? [duplicate]

If I hit an object with a pen for example, does the pen touch the atoms on the surface of the object? Won't it damage the atoms? If I can't touch it, then where does the sound come from?

Let's analyze this problem. Very idealistically, the energy with which the pen of mass $m$ hits the object is given by $$E = \frac{1}{2} I \omega^2,$$ where $I$ is the moment of inertia defined about an axis and $\omega$ is the angular velocity of the pen. Or even $$E = mgh,$$ where $g$ is the contribution from gravity and $h$ is the height from which it was dropped. Now let this setup hit the object and we find that if the object were classical with some defined repulsive potential $V_{obj}$, then the objects can touch iff $E \sim V_{obj}$, up to a few small corrections. Try and work out the answer for a pen of weight a few grams hitting the object with some velocity. You will find that this is not even close to overcoming the potential barrier due the electrons. This is because if the two atoms try to get too close to each other, they will experience a strong repulsive force. This force is quite strong, at least stronger than the energy dispersed by hitting a pen to an object.