Question

Explain why, we can easily move our hand in air but to do the same through a plank of wood, we need a karate expert.

Answer 1

We can move our hand easily in air because the force of attraction between the particles of air is very small, as there are large inter-molecular spaces in air. However, we can’t move our hand through a plank of wood because the force of attraction between the particles of wood, which is a solid substance, is very strong and the inter-molecular spaces are negligible. That is the reason why we can’t move our hand through a plank of wood and need a karate expert to do so.