An assembly line uses 4 workstations. The total task times in minutes are 15, 20, 15 and 10. What is the line efficiency if the cycle time is 20 minutes?

f=ma a/f/m a= 480/60 a = 8m/s/s that is quick wow

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.

there are no contact forces mentioned on the list of choices that you've provided.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.