Question

Give reason: we can easily move our hand in air but to do the same through a solid block of wood we need a karate expert

Answer 1

because the particles of solids are tighty compressed and we have to make more force to make escape them but in air there is very little force of attraction b/w them so we dont want more force to escape

Answer 2

we can move our hand easily in air because the particles of air are loosely packed and the force of attraction between particles of air is weak but on the other hand particles in solids are tightly packed and more force of attraction of particles is there so we need a karate expert.