Length in Feet (2)

[Guest]

A coil of steel wire weighs 50 lbs., diameter 0.025 in. Steel weighs .283 lbs. / cu. in. Determine length of wire.

The wire is a regular cylinder.

Area of circle; pi * r^2.

3.1416 * 0.0125 * 0.0125 = 0.0049 sq. in.

0.0049 * 1 = 0.0049 cu. in. (volume of 1 ft.)

50 / .283 = 176.678 = 177 cu. in. (vol. of wire).

177 / 0.0049 = 36122.48 ft.

Answer provided is less. Where am I correct ?

[Guest]

0.0049 * 1 = 0.0049 cu. in. (volume of 1 ft.)
I think this should be 0.00049 cu.in

is your answer about 10 times too small

I get 359926.37

and divide that by 12 to get feet = 29993.9 feet
divide by 3 gets 9998 yards
divide by 1760 gets 56.8 miles

[Guest]

Sorry, no the last post is totally wrong.....

3.1416 * 0.0125 * 0.0125 = 0.0049 sq. in. this is square inches

0.0049 * 1 = 0.0049 cu. in. (volume of 1 ft.) ....If this is cubic feet you need to convert

3.1416 * 0.0125 * 0.0125 = 4.909 * 10^-4 = 0.0004909 sq.ins

1 foot length is 12 inches...... and find how many feet

volume of 1 foot length = 0.0004909 x 12 = 5.89 * 10^3 = 0.00589 cu ins

50 / .283 = 176.678 = 177 cu. in. (vol. of wire).

177 / 0.00589 = 30050.9 ft. = 5.69 miles

[Guest]

Thanks.

Just for follow-up;

Answer given: 29,270 (nearly).

How did they get a lower answer ?

[Guest]

A coil of steel wire weighs 50 lbs., diameter 0.025 in. Steel weighs .283 lbs. / cu. in. Determine length of wire.

You need to be careful with "roundings" especially when dealing with very large quantities of very small numbers or vice versa.

We will work it out with no or minimal roundings......

Area of circle is Pi* r * r

Take Pi as your figure ..... 3.1416 .....which is actually a rounded figure to 4 decimal places

1 foot length is 12 inches ...find how many feet in quantity of material.

Volume of 1 foot of wire ... 3.1416 * 0.0125 * 0.0125 * 12 = 0.0058905 cu.ins

Volume of material ..... 50 / 0.283 = 176.67845 cu.ins

Length of wire (how many feet) .... 176.67845 / 0.0058905 = 29993.794 feet



Some take Pi as 22/7 = 3.1428571 according to my calculator ..............

Volume of 1 foot of wire ... 3.1428571 * 0.0125 * 0.0125 * 12 = 0.0058928571 cu.ins

Volume of material ..... 50 / 0.283 = 176.67845 cu.ins

Length of wire (how many feet) .... 176.67845 / 0.0058905 = 29981.798 feet


The Pi constant in my calculator is ..... 3.1415927

Volume of 1 foot of wire ... 3.1415927 * 0.0125 * 0.0125 * 12 = 0.0058904862 cu.ins

Volume of material ..... 50 / 0.283 = 176.67845 cu.ins

Length of wire (how many feet) .... 176.67845 / 0.0058904862 = 29993.865 feet


The conversion ..... Steel weighs .283 lbs. / cu. in. may also be a rounded figure....?????

[Guest]

Thanks again; that helps.

" The conversion ..... Steel weighs .283 lbs. / cu. in. may also be a rounded figure....????? " I have seen various charts of material weights, showing 0.28, 0.283, .28, and .283. I guess the number could be carried to more places.

[leesajohnson]

3.1416 * 0.0125 * 0.0125 = 0.0049 sq. in.

0.0049 * 1 = 0.0049
50 / .283 = 176.678 = 177

177 / 0.0049 = 36122.48 ft.