Question

A steel reinforcing rod is 12 ft. long and 1" thick in diameter. If a cubic foot of steel weighs 490 lb., how much does the rod weigh (to the nearest pound)?

Answer 1

32 pounds

Explanation:

Answer 2

In cubic feet, the volume of the rod is given by the formula for the volume of a cylinder.
.. V = (π/4)*d^2*h
.. = (π/4)*(1/12 ft)^2*(12 ft)
.. = π/48 ft^3

Then the weight is
.. (490 lb/ft^3)*(π/48 ft^3) ≈ 32 lb