A toy cart moves with a kinetic energy of 30 J. If its speed is doubled, what is its kinetic energy?

Explanation:

KE is directly proportional to the square of velocity / speed.

if speed is 2 times (doubled) the KE will be

= 4 times the original KE

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.