Amount in Feet

[Guest]

Allowing 5% for waste, determine amount in feet of lead pipe 2 in. outer diameter, 1/4 in. thick from a ton of lead. A cu. ft. of lead weighs 710 lbs. A pipe is considered a cylinder.

.95 * 2000 = 1900 lbs. (amt. of material).

Area of circle; pi * r^2

Outer; 3.1416 * 1 * 1 = 3.1416 sq. in.
Inner; 3.1416 * .75 * .75 = 1.76 sq. in.

3.1416 - 1.76 = 1.38 sq. in. / 144 = .00958 sq. ft. (area of end).

Volume of cylinder; pi * r^2 * height (or length).

Unsure how to continue.

[Guest]

Volume of cylinder; pi * r^2 * height (or length). OR this is Area of end * height or length
So...... Volume of pipe (hollow cylinder) = Area of end * height(or length}

Do the sum the same way as the marbles question was done

Find volume of object.
Find weight of object
Find weight of materials available after allowing for waste
Divide object weight into material weight to find number of objects

[Guest]

.95 * 2000 = 1900 lbs. (material available).

1900 / 710 = 2.676 = 2.68 cu. ft. (volume of material).


" Find volume of object.
Find weight of object. " I don't know how.

[Guest]

This is the question......
Allowing 5% for waste, determine amount in feet of lead pipe 2 in. outer diameter, 1/4 in. thick from a ton of lead. A cu. ft. of lead weighs 710 lbs. A pipe is considered a cylinder.

A pipe is considered a cylinder. .......but it is a hollow cylinder.......OR in fact 2 hollow cylinders one inside the other and the difference (volume or end area) is the pipe material in between.

Volume of cylinder; pi * r^2 * height (or length). OR this is Area of end * height or length
So...... Volume of material in a pipe (hollow cylinder) = Area of end * height(or length}

Do the sum the same way as the marbles question was done.....in marbles question you were asked for "how many marbles"
In this question you are asked for what length in feet...OR.....how many feet...... to keep it simple and the same consider the 1 foot length as an object and find how many feet or objects.

How to do it..................

Find volume of object.
Find weight of object
Find weight of materials available after allowing for waste
Divide object weight into material weight to find number of objects

...............................................

What you have done so far ......................

.95 * 2000 = 1900 lbs. (amt. of material).

Area of circle; pi * r^2

Outer; 3.1416 * 1 * 1 = 3.1416 sq. in.
Inner; 3.1416 * .75 * .75 = 1.76 sq. in.

3.1416 - 1.76 = 1.38 sq. in. / 144 = .00958 sq. ft. (area of end).

Volume of cylinder; pi * r^2 * height (or length)......Yes, or area of end * length

Unsure how to continue. ......??????

Consider 1 foot length ......

Volume of 1 foot length of pipe is.....0.00958 * 1 = 0.00958 cu.ft


You have already found the amount of material and its volume.......

.95 * 2000 = 1900 lbs. (material available).

1900 / 710 = 2.676 = 2.68 cu. ft. (volume of material).

So how many (1 foot lengths) can be made from this volume...????

Divide total volume by the object volume........

So..... 2.676 / 0.00958 = 279.33 .... so... 279.33 feet of pipe can be made from a ton of lead.

[Guest]

Ok, thanks.

A question: If the weight per cu. in. was given, would the problem be done basically the same ?

[Guest]

I think I figured it out;

Lead weighs .41 lbs. / cu. in.

1900 / .41 = 4634.14 cu. in.

pipe vol.; 1.337375 (unchanged).

4634.14 / 1.37375 = 3373.35 in. = 281 ft.

Where am I correct ?

[Guest]

How to do it..................

If given the density of lead in lbs per cu.ins.......
Convert the lead "lbs per cu.ins" to "lbs per cu.ft then do as before....
There are 12 * 12 * 12 cu.ins in 1 cu.ft.

Find volume of object.
Find weight of object
Find weight of materials available after allowing for waste
Divide object weight into material weight to find number of objects

[Guest]

" Convert the lead "lbs per cu.ins" to "lbs per cu.ft then do as before...." I wanted to work in just cu. in.

[Guest]

If you want to work in cu.ins then work everything out based on cu.ins ...it is the same type of procedure

Find volume of object. .......consider 1 inch length of pipe, find area of end in sq.ins and multiply by length of 1 inch to get volume of 1 inch of pipe in cu.ins.

Find weight of object ..... weight of 1 inch length of pipe

Find weight of materials available after allowing for waste ....will be same as before in lbs.

Divide object weight into material weight to find number of objects .....now it will be the number of inches of pipe

Then to answer the original question convert this length to feet.

[Guest]

.95 * 2000 = 1900 lbs. (amt. of material).

Weight : .41 lbs. / cu. in.

1900 / .41 = 4634.14 cu. in. (vol. of material).

Area of circle; pi * r^2

Outer; 3.1416 * 1 * 1 = 3.1416 sq. in.
Inner; 3.1416 * .75 * .75 = 1.76 sq. in.

3.1416 - 1.76 = 1.38 sq. in.

1.38 * 1 = 1.38 cu.in. (volume of 1 in.)

1.38 * .41 = 0.5658 lbs. (weight of 1 in.)

4634.14 / 1.38 = 3358.07 in. / 12 = 279.83 = 280 ft.

Not sure.

[Guest]

Yes, OK, correct, but you didn't follow my outline sequence of calculations

You found the volume of material and divided by the volume of the object.

We already knew the weight of the materials so I outlined divide by weight of object.

it gets the same answer...with less calcs...

[Guest]

I will follow your sequence:


'" Find volume of object. .......consider 1 inch length of pipe, find area of end in sq.ins and multiply by length of 1 inch to get volume of 1 inch of pipe in cu.ins.

Outer; 3.1416 * 1 * 1 = 3.1416 sq. in.
Inner; 3.1416 * .75 * .75 = 1.76 sq. in.

3.1416 - 1.76 = 1.38 sq. in.

1.38 * 1 = 1.38 cu.in. (volume of 1 in.)


Find weight of object ..... weight of 1 inch length of pipe 1.38 * .41 = 0.5658 lbs.

Find weight of materials available after allowing for waste ....will be same as before in lbs. .95 * 2000 = 1900 lbs.
Divide object weight into material weight to find number of objects .....now it will be the number of inches of pipe 1900 / .41 = 4364.14
Then to answer the original question convert this length to feet. "

I can't solve it.

[Guest]

Find weight of object ..... weight of 1 inch length of pipe 1.38 * .41 = 0.5658 lbs. ..........yes

Find weight of materials available after allowing for waste ....will be same as before in lbs. .95 * 2000 = 1900 lbs. ......yes
Divide object weight into material weight to find number of objects .....now it will be the number of inches of pipe 1900 / .41 = 4364.14 ........no this is not the material weight divided by the object weight...??????

Then to answer the original question convert this length to feet. "

[Guest]

I can't solve.

[Guest]

You have it already solved..............

Find weight of object ..... weight of 1 inch length of pipe 1.38 * .41 = 0.5658 lbs. ..........yes

Find weight of materials available after allowing for waste ....will be same as before in lbs. .95 * 2000 = 1900 lbs. ......yes ...IF I say this is the weight of the object.......will you notice it now......

Divide object weight into material weight to find number of objects .....now it will be the number of inches of pipe 1900 / .41 = 4364.14 ........no this is not the material weight divided by the object weight...??????

Then to answer the original question convert this length to feet. "

[Guest]

I meant it to relate to the line above in last post...........

You have it already solved..............

Find weight of object ..... weight of 1 inch length of pipe 1.38 * .41 = 0.5658 lbs. ..........yes.......IF I say this is the weight of the object.......will you notice it now......

Find weight of materials available after allowing for waste ....will be same as before in lbs. .95 * 2000 = 1900 lbs. ......yes ...

Divide object weight into material weight to find number of objects .....now it will be the number of inches of pipe 1900 / .41 = 4364.14 ........no this is not the material weight divided by the object weight...??????

Then to answer the original question convert this length to feet. "

[Guest]

" Divide object weight into material weight to find number of objects " 1900 / 0.5868 = 3237.90 = 3237.900

" Then to answer the original question convert this length to feet. " 3237.900 / 12 = 268.825 = 269

I don't know.

[Guest]

" Divide object weight into material weight to find number of objects " 1900 / 0.5868 = 3237.90 = 3237.900

" Then to answer the original question convert this length to feet. " 3237.900 / 12 = 268.825 = 269

How many times can a sum be wrong before it is right.........?????????

" Divide object weight into material weight to find number of objects " 1900 / 0.5658 = 3358.08

" Then to answer the original question convert this length to feet. " 3358.08 / 12 = 279.84 ..... so 279 feet of pipe

[Guest]

" How many times can a sum be wrong before it is right.........????????? " Sorry I posted the wrong number (0.5868 instead of 0.5658).