Not at all. Density on its own is not sufficient
True . this is called a complex substance
They have similar physical and chemical properties because of thier valence electrons
Wee can use here kinematics
as we know that

for shorter tree we know that


now since we know that other tree is twice high
So height of other tree is y = 39.2 m
now again by above equation



so the time taken is 2.83 s