What is the volume of metal used in the pipe shown?
- 45pi cm^3
- 4500pi cm^3
- 18000pi cm^3
Explanation from PART66Online
The metal is the ring-shaped cross-section multiplied by the length. The radii are 5 cm and 4 cm, so the cross-section is pi x (5 squared - 4 squared) = 9 pi square centimetres, and the length is 5 m = 500 cm: V = 9 pi x 500 = 4500 pi cm^3. Using the diameters instead of the radii gives pi x (100 - 64) x 500 = 18000 pi, four times too much, and leaving the length as 5 instead of 500 cm gives 45 pi.
R
roshraj asked · 28 Jul 2013
how did u get this answer
Community Comments (8)
P
PART66Online
28 Jul 2013
Hey.
1) Calculate volume of cylinder using outer diameter.
2) Calculate volume of cylinder using inner diameter.
3) Subtract from result 1 result of 2.
1) Calculate volume of cylinder using outer diameter.
2) Calculate volume of cylinder using inner diameter.
3) Subtract from result 1 result of 2.
R
roshraj
28 Jul 2013
thnks buddy
M
Macaw1986
13 Nov 2013
My calculations are different
If OD is BA=rπ2 I get 5cm(π)=15.7 BA x L = 15.7cmx500cm=7853cubed
If ID is BA=rπ2 I get 4cm(π)=12.56 BA x L=12.56cmx500cm=6283cubed
Assuming the center of the pipe is air I subtract 6283 from 7853 and that gives me 1570 cubic inches of metal.
If OD is BA=rπ2 I get 5cm(π)=15.7 BA x L = 15.7cmx500cm=7853cubed
If ID is BA=rπ2 I get 4cm(π)=12.56 BA x L=12.56cmx500cm=6283cubed
Assuming the center of the pipe is air I subtract 6283 from 7853 and that gives me 1570 cubic inches of metal.
P
PART66Online
13 Nov 2013
Hello Mascaw.
You messed everything. :)
Why inches? No one asks you about volume in inches.
Here is correct calculation:
1) Volume using outer diameter is: V = r^2 * h * π = 5^2 * 500 * π = 12500π
2) Volume using inner diameter is: V = 4^2 * 500 * π = 8000π
3) Volume of metal used in this pipe: V = 12500Ï€ - 8000Ï€ = 4500Ï€
You messed everything. :)
Why inches? No one asks you about volume in inches.
Here is correct calculation:
1) Volume using outer diameter is: V = r^2 * h * π = 5^2 * 500 * π = 12500π
2) Volume using inner diameter is: V = 4^2 * 500 * π = 8000π
3) Volume of metal used in this pipe: V = 12500Ï€ - 8000Ï€ = 4500Ï€
M
Macaw1986
14 Nov 2013
I meant CM sorry,I am a very compulsive typist.
It seems you are not multiplying pie. I multiply 5^2*500 I get 12500.
Pardon me if I am way wrong it has been a while as I took my Air frame and power plant exam 3 years ago.
I went to an online calculator and it got different results as well.
onlineconversion.com/object_volume_cy...
It seems you are not multiplying pie. I multiply 5^2*500 I get 12500.
Pardon me if I am way wrong it has been a while as I took my Air frame and power plant exam 3 years ago.
I went to an online calculator and it got different results as well.
onlineconversion.com/object_volume_cy...
M
Macaw1986
14 Nov 2013
Meant Pi. did it again.
P
PART66Online
14 Nov 2013
Yes, pi is not calculated here, it is shown in all possible answers. Assuming what you will calculate this task on paper, it is not easy to calculate it fully fast and correct. Main purpose of this questions is to check do you know volume of cylinder formula or not. :)
M
Macaw1986
14 Nov 2013
thank you for the clarification.
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