Answer:
That's a long one... Read below for the answer
Step-by-step explanation:
The national government is a democracy, the 3 branches are the executive branch, legislative branch, and judicial branch.
The executive branch is mainly the president. This branch also handles diplomacy with other nations.
The legislative branch is mainly the constitution. It creates laws and develops a "social contract" between us. Some people even call it the most powerful branch.
Judicial branch is mainly the supreme court. It interprets laws and the citizens choose state judges.
Moving onto the relationship of the national government and the state governments. I should say; Federalism. State governments follow national regulations and can regulate within their state boundaries.
The "elastic clause" was specifically made so that government can keep up with MODERN THOUGHTS. The founders knew it would be necessary because, to put it simply, nothing stays the same.
I hope this answers your questions! Good luck!