A 2.0-kg block sits at the top of an inclined plane with a length of 4.12 m. If the coefficient of kinetic friction μk is 0.18 between the block and the plane, how long will it take the block to slide down the plane when released?

2.16sec

Explanation:

Data;

Mass = 2.0kg, a = 4.12m, u = 0.18, t = ?

F = μN

F = ma and N = mg

ma = μmg

Mass cancels out on booths sides,

Therefore,

μ = a / g

a = μg = 0.18*9.8

a = 1.764m/s²

Using equation of motion,

S = ut + ½at²

But u = 0m/s since the body is at rest

4.12 = 0 + ½ * 1.764 * t²

4.12 = 0.882t²

t² = 4.12 / 0.882

t² = 4.6712

t = √(4.6712)

t = 2.16s

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.