A moving rail car collides with a stationary car that has identical mass, and the two cars begin to move together. If the momentum of the moving car was 450,000 kg•m/s, what is the total momentum of the two cars after the collision? A. 225,000 kg•m/s
B. 450,000 kg•m/s
C. 900,000 kg•m/s
D. Total momentum cannot be determined from this information.

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.

attach the statements so i can answer : )