Which has the greatest effect on the flow of fluid through a ...

[formula1]

Which has the greatest effect on the flow of fluid through a pipe? That is, if you made a 10 change in each of the quantities below, which would cause the greatest change in the flow rate?
 
  A) the fluid viscosity
  B) the length of the pipe
  C) the pressure difference
  D) the radius of the pipe
  E) the fluid density

Question 2

Why might it be difficult for Earth-like planets to form around Sun-like stars in the outer parts of the disk of our galaxy?
 
  A) there would be insufficient amounts of heavy elements
  B) the stars would be packed together too densely for planets to be stable
  C) any stars would be sucked into the central supermassive black hole
  D) there would be too much harmful radiation

[bbburns21]

Answer to Question 1

D

Answer to Question 2

A

[formula1]

Excellent

[lkanara2]

Thanks for the timely response, appreciate it