Question 1060496
A concrete pipe has length 10 feet, outer diameter 4 feet and thickness 3 inches.  To the nearest 100 pounds, how much does it weigh?  (Concrete weighs 150 lb/ft3.)
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For a cylinder:
{{{Vol = pi*r^2*h}}}
h = 120 inches
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find the volume of the outside cylinder: r = 24 inches
Subtract the volume of the inside cylinder: r = 18 inches
--> Vol in cubic inches.
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Multiply volume by density.
1 cu ft = 12*12*12 = 1728 cu inches
150 pounds/cu ft = 150/1728 pounds/cu inch