Define 1 second time​

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

Although longitudinal waves can travel through all media types what is the disadvantage of this type of wave transmission? a) he efficiency of he wave transmission is greatly diminished as the media becomes less dense b) the oscillation of one set of particles has a huge impact on neighboring particles c) particles become too close together as they bump into each other making it more likely to hit other particles down the line

Aspacecraft that renters the earth’s atmosphere drastically slows down. the amount of kinetic energy the spacecraft has as it reenters the earths atmosphere