Explain why the box may continue to move forward if the cart suddenly stops moving

The box and the cart have inertia. If the cart goes to a unexpected stop, the box tends to move forward continuously . When it starts moving again ( the cart ) , there's no movement in the box. The box moves forward because the cart unleashes an unbalanced force on the box

Hope it helps =)

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.