How do the nucleus and ribosomes interact in the process of protein synthesis?
The nucleus and ribosomes don't personally, physically interact in the process of protein synthesis. They are both involved, but in different ways and at different points in the process.
The analogy I usually use is that the cell is like a factory. The nucleus is like the boss, RNA instructions are the boss's orders, the ER is the factory floor, and the ribosomes are the workers.
The ribosomes can't make protein without a set of RNA instructions. It bears repeating that none of the components of the cell are conscious, sentient or "smart", and despite the language that we sometimes use to make things easier to understand, the cell components never "know" what's going on, nor are they able to make independent decisions. They simply follow chemical instructions. If the ribosomes never receive those instructions, they don't go looking for them, or bide their time by practicing. They just don't do anything.
The best way of describing their relationship is by relating their roles in the protein production process. The nucleus controls the production of proteins by sending RNA instructions to the ribosomes. The ribosomes depend upon the nucleus to send RNA instructions for protein synthesis.