Question

Find the volume and solve the application. A steel post is 6 ft. long and 6” thick in diameter. If a cubic foot of steel weighs 490 lb., how much does the rod weigh (to the nearest pound)?

1.) 138
2.) 332
3.) 338
4.) 577

Answer 1

577

Explanation:

Answer 2

Answer choice 4. 577 pounds

Explanation:

Given a cylindrical steel post with dimensions:

• length/height = 6 ft

• Radius = half of diameter = 0.5 * 6 = 3 inches [converting to feet, we need to divide inches by 12, so we have
  `(3)/(12)=0.25` feet ]

Volume of a cylinder is given as:

Volume =
`\pi r^(2)h`

Substituting all the given values we have:

`V=\pi r^(2)h\\V=\pi(0.25)^(2)(6)\\V=0.375\pi\\V=0.375(3.14)\\V=1.1775` cubic feet

Since, 1 cubic foot of steel weights 490, 1.1775 cubic foot of steel would weigh
`490*1.1775=576.97`

Rounding to nearest pound, we would get
`577` pounds as the answer.

Answer choice 4 is correct.