Logs sometimes float vertically in a lake because one end has become water-logged and denser than the other. What is the average density (in kg/m3) of a uniform-diameter log that floats with 60.0% of its length above water

the average density (in kg/m3) of the log is 400 kg/m³

Explanation:

Given that;

a log with uniform-diameter floats with 60.0% of its length above water.

from the Archimedes principle formula;

friction submerged = Average density of object / density of fluid. --- equ 1

We know that; density of water = 1000 kg/m³

now the log floats with 60.0% of its length above water

so submerged fraction is 100% - 60% = 40% = 0.40

from our equation;

friction submerged = Average density of object / density of fluid

we substitute

0.40 = Average density of object / 1000 kg/m³

Average density of object  = 0.40 × 1000

Average density of object  = 400 kg/m³

Therefore; the average density (in kg/m3) of the log is 400 kg/m³