Question

we can easily move our hand in air but do the same as solid block of wood we need a karate expert

Answer 1

air has no bond on it so we move our hand in easy way but in wood there is more bond on it but crate expert have experience that how pas there hand but they brust it but not move their hand easily

Answer 2

it is because the particles of air are loosely placked so we can break the force of air with movement of our hand but in case of solid block which is tightly packed the innermolecular forces are more which we cannot break easily so we need a karate expert