2. a 20 gram bullet exits the rifle at a speed of 985 m/s. the gun barrel is 0.8 m long. What was the force during the firing. 3. A force of 380 N is applied to a 38 kg object over a distance of 2.5 meters. What is the speed
of the object after it accelerates?
4. A 21,000 kg train is traveling at 21 m/s. It accelerates as it enters a tunnel because of a constant force of 45,000 N from the engine. The train is in the tunnel for 5.25 seconds. What is the final speed of the train?

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.