How to understand "Four great elements" in real life objects?

I have some understanding about the "Four great elements" But i have these questions... My chair is solid **wood**, So i understand the "Solidity element (Patavi)" but how do i understand the rest of the elements in it *Expansion* My chair is solid **Iron**, So i understand the "Solidity element (Patavi)" but how do i understand the rest of the elements in it -------------- My chair is Plastic, So i understand the "Solidity element (Patavi)" but how do i understand the **"State of flowing or Fluidity element"** in it