How to explain the principle of balance with lever

How to explain the principle of balance with lever

The balance crossbeam is supported on a knife edge of the base, which is the fulcrum. The crossbeam is adjusted by the balance nut to make the center of gravity just fall on the knife edge, and the distance between the center of the two pallets and the knife edge is the same, so that the balance becomes an equal arm lever

How many years did Archimedes discover the lever principle?

Yes, he said to use a pole to lift the earth

On Archimedes theorem
Why is buoyancy = the gravity of the liquid to be drained = the gravity of the object itself when floating or levitating?
There's another little question: the gravity of the drained liquid = the mass of the drained liquid times G
Gravity of object = mass of object multiplied by g. the mass of liquid and mass of object do not want to wait. How can the gravity of object be equal to the gravity of object itself? It may be a bit complicated, but I really don't understand

When floating or levitating, buoyancy = the gravity of the displaced liquid = the gravity of the object itself
Because the object is balanced, the resultant force is zero!
The mass of the liquid and the mass of the object do not want to wait, the object will sink to the bottom!

On the third grade physics -- lever principle
In the research of leverage balance conditions
(1) In addition to lever, bracket, fine thread and hook code, the necessary equipment is also needed______ ;
(2) What is the function of the nuts at both ends of the lever__________________ .
I have a total of 668 points, a lot of

(1) In addition to lever, bracket, thread and hook, the required equipment also needs (spring dynamometer)
(2) The function of the nuts at both ends of the lever is to (adjust the lever balance)