Two moons orbit a planet in nearly circular orbits. Moon A has orbital radius r, and moon B has orbital radius 16r. Moon A takes 10 days to complete one orbit. How long does it take moon B to complete an orbit

Kepler's Third Law:  The square of the period of any planet about the sun is proportional to cube of its mean distance from the sun.

Mathematically:  T^2 = K R^3

So  (TA / TB)^2 = (RA / RB)^3

TB^2 = TA^2 * (RB / RA)^3

TB^2 = 10^2 * 16^3

TB = (409600)^1/2 = 640 days

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.