Archimedes principle states

Copper has free electrons per cubic meter. a 71.0-cm length of 12-gauge copper wire that is 2.05 mm in diameter carries 4.85 a of current. (a) how much time does it take for an electron to travel the length of the wire? (b) repeat part (a) for 6-gauge copper wire (diameter 4.12 mm) of the same length that carries the same current. (c) generally speaking, how does changing the diameter of a wire that carries a given amount of current affect the drift velocity of the electrons in the wire?

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

An object weigh 40n in air ,weigh 20n when submerged in water, and 30n when submerged in a liquid of unknown liquid density. what is the density of unknown of liquid?