Aparachutist, after opening her parachute, finds herself gently floating downward, no longer gaining speed. she feels the upward pull of the harness, while gravity pulls her down. which of these two forces is greater? or are they equal in magnitude?

Since parachutist is moving downwards with constant speed

so here we can say

acceleration is rate of change in velocity

since velocity is given constant here

So acceleration in this case will be zero

now we know from Newton's II law

here a = 0

here

= force due to gravity

= force due to buoyancy

So here we can say

so

so upward force on it will be balanced by downward force.

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.

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.