Answer: the average density (in kg/m3) of the log is 400 kg/m³
Step-by-step 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