a farmer wants to irrigatre her land in 9 hrs. the area of her field is 25 acres. she grows alfalfa that requires 3 inches of water during the 9hrs. at what flow rate should she pump the water? provide answer in gal/min.
i converted acres and inches to feet to determine the volume and then converted that into gallons. the part that is confusing me is to figure out the flow rate.
2007-09-10 07:54:26 · 5 answers · asked by ♡♥EM♡♥ 4 in Science & Mathematics ➔ Engineering
25 acres * 3 inches = a volume of 1089004 * 0.25 = 272251 cubic feet = 2036579 gallons
2036579 gallons / 9 hours =
2036579 gallons / 9 hours * 1 hour / 60 minutes =
504 gal/minute
You have gallons per hour and you know there are 60 minutes in 1 hour, so divide te gallons per hour number by 60 to get gallons per minute.
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2007-09-10 08:02:58 · answer #1 · answered by tlbs101 7 · 0⤊ 0⤋
You are on the right track. In problems like this always pay attention to the units, and track them carefully (which ones cancel, which ones become squared, which ones become products, i.e. foot-pounds)
Figure out the total amount of water needed to be delivered.
So you need to figure out how much water is needed to deliver 3 inches across 25 acres. (The result should be in cubic inches.)
Now convert it to gallons (there should be a conversion chart to use for this). Then it should be straightforward to calculate the flow-rate to deliver that amount in 9 hours (which can easily be converted to minutes). Like I said, just pay close attention to units.
(I see by the time I entered my answer, some others beat me to it....but my goal was to help YOU FIND the answer, not just tell it to you.)
2007-09-10 15:11:16 · answer #2 · answered by Anonymous · 0⤊ 0⤋
1 acer = 6272640 in^2
25 acers =156816000.
volume of water = 3 * 156816000 = 470448000 cubic inches
time = 9hours * 60 = 540 minutes
flow rate = volume / time = 470448000/540 =871200 inch/minute
1 gallon = 231 cubic inches
so devide the flow rate by 231 and u will get it in gallons per min
flow rate = 3771 gallons per min
2007-09-10 15:48:25 · answer #3 · answered by koki83 4 · 0⤊ 0⤋
1 acre = 43 560 sq feet
25 acres = 1 089 000 sq ft
3 in = 1/4 ft
farmer needs 1 089 000 x 1/4 cu ft
= 272,250 cu ft of water in 9 hr
flow rate = volume / time
= 272250 / 9 = 30,250 cu ft / hour
2007-09-10 15:03:53 · answer #4 · answered by vlee1225 6 · 0⤊ 0⤋
1 acre = 43,560 ft² x (25 acres) x (0.25ft depth of water (3"))
= A water volume of 272,250 ft³
1 ft³ of water = 7.5 US gallons.
272,250 x 7.5 = 2,041,875 gals.
9 hrs = 9 x 60min. = 540min.
2,041,875gal ÷ 540min = 3,781.25 gal/min required.
2007-09-10 19:16:41 · answer #5 · answered by Norrie 7 · 0⤊ 0⤋