1.Stu the Implausible, the renowned daredevil and stuntman, has strapped a jet engine to his dragster and is racing across the plains of Nevada trying to break the sound barrier. He travels a glorious 1000 meters in 3.7 seconds. What was his average velocity? [Bonus: did he break the sound barrier or no? Explain] how can i tell if he broke the sound barrier?

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.

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.