Question

what am i doing wrong?
A copper pipe, used for plumbing from the water main to a house, is 4 meters long and has a circular cross-section 2.8 cm in diameter. There is a 2 cm diameter hole in the center of the cross-section for the entire length of the rod. What is the volume of copper in the rod in cubic inches?

The density of copper is 559lb_m/ft^3 . What is the mass of the copper pipe in pounds?

in caculating the mass of copper what am i doing wrong?
pi(1.4)^2*500-pi(1)^2*500= 1507.9
1507.9 * 01974=29.76 lbs

Answer 1

hold on, i'm trying to understand the question

Answer 2

ok

Answer 3

it's 400 centimeters u're multiplying by 500

Answer 4

Does that answer your question?

Answer 5

can you help me with finding the cubic inches

Answer 6

volume of cooper in cubic inches

Answer 7

Well is this answer right in centimeters:
1507.9 cm^3 ? I don't think so, because u multiplied by 500, when u were supposed to multiply by 400

Answer 8

ocond part of the question, i now understand. can you help me with first part pls

Answer 9

second

Answer 10

which part do u need help with? First?

Answer 11

yes

Answer 12

No that's the thing the 2nd part depends on the first and the first part is wrong. Anyway..

Answer 13

i was able to find the mass pounds without doing the cooper

Answer 14

I believe the diameter was given in the question and the cross section is area of the circle, which means you should be using Area = Pi * radius ^2

Answer 15

If we use the correct numbers:

pi(1.4 cm)^2*400 cm-pi(1 cm)^2*400 cm = pi(1.4 * 0.39 in)^2*400 cm-pi(1 * 0.39 in)^2*400 * 0.39 in

Answer 16

One cm is 0.39 inches, so all you gotta do is just convert your centimeters into inches in the formula and that's it

Answer 17

woops forgot to multiply by 0.39 at one point
pi(1.4 * 0.39 in)^2*400 * 0.39 in-pi(1 * 0.39 in)^2*400 * 0.39 in =

Answer 18

71.568in^3 is the volume

Answer 19

thanks