SOLUTION: The flow rate of water (F cm^3/s) in a water pipe varies directly as the square of the diameter (D cm) of the water pipe.The flow rate of water is 720 cm^3/s when the diameter is

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Question 987441: The flow rate of water (F cm^3/s) in a water pipe varies directly as the square of the diameter (D cm) of the water pipe.The flow rate of water is 720 cm^3/s when the diameter is 30 cm.
(a) Express F in terms of D.
(b) Find the flow rate of air in a water pipe with diameter 25 cm.
My answer
(a) F=k(D^2)
720=k(30^2)
k=(4/5)
(b) let F cm^3/s be the flow rate of air
F=k(D^3)
F=(4/5)(25^2)
F=500 cm^3/s
This are my answers i am not sure is these answers are right or wrong.
Please help me solve this problem.
Thank you for your kind attention.
Looking forward for your reply.

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Your work for part (a) is good, but part (b) turned your question into a physics or flow dynamics problem, so either someone with this kind of knowledge needs to respond, or you made a mistake in identifying your material for the problem. If you stay with water, then you have your formula for F.