Question

we can easily move our hair in air but you to do the same thought a solid block of wood or Break we need a Karate expert explain why

Answer 1

intermolecular forces in air are very weak forces of attraction between them. it is very weak to hold the particles. so, by applying force with our hand, we can overcome this force. in case of solid wooden block, the intermolecular forces are very strong, the forces of attraction between them are high. this force is able to hold the particles strongly. so, greater force from outside is required to break a wooden block which could be done by a karate expert.
hope this answer will help you.

Answer 2

Air is a gas, it has more space in between particles. But solid block of wood is rigid, hence it is difficult to move our hands through it.