A log with a mass of 15 kg is on free fall from the top of a mountain. When it is at a height of 28 m from the ground level, it has a velocity of 70 m/s. a. What is its mechanical energy at this position?

Explanation:

Potential energy = mgh=15*28*10=4200 J

Kinetic Energy = 1/2mv^2 =1/2*15*70^2=36750J

Total Mechanical Energy = 4200J+36750J=40950J

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.