Factors affecting buoyancy. Then explain the principle of submarine ups and downs.

Buoyancy is equal to the gravity of the liquid displaced by the object. It depends on the density of the liquid and the volume of the displaced liquid. In the same liquid, the buoyancy of an object is only related to the volume of the displaced liquid.

If the submarine dives completely, the buoyancy will remain unchanged, because the volume of liquid it displaces is its volume, which is certain. Submarines can suck water into the boat or discharge it out of the boat, so the weight of the submarine is changing, that is, the gravity on the submarine is changing. When the submarine gravity is greater than buoyancy, dive; On the contrary, floating; When the two are equal, they are suspended.