







Two intersecting tubes 
20180815 

From Tommy: Hi, I am trying to determine a mathematical model for two metal tubes joining at various degrees for weld.
For instance, if I am trying to join the end of a tube to the side of another at a 90 degree angle, it will be a simple profile cut out of the joining tube.
Where it gets tricky is if you want to join the new tube at a given angle.
It would be very helpful if you could give insight as to how I can solve this problem or an equation I could work off of.
Thanks for the help!! Answered by Edward Doolittle. 





The volume of a round tube 
20120207 

From I.C: I need to find out how long a 10" round tube needs to be in order for there to be .95 cubic feet of air space Answered by Harley Weston. 





The outside surface area of a U shaped tube 
20100603 

From Adolfo: What is the formula for calculating the outside surface area of a U shaped tube? Answered by Robert Dawson. 





The volume of a test tube 
20100520 

From Nick: A maths question. I have a test tube (basically a cylinder but with a rounded
bottom end) and the measurements are: the diameter or width of the tube is
31mm and the total length of the whole tube is 204mm. The question is:
(a) what's the volume of this test tube (rounded to the nearest cubic mm) and
(b) what's the capacity of this test tube (rounded to the nearest mL).
I need to show the full mathematical workings out of the two, not just the
answer. The problem is the circular bottom end of the tube, it isn't flat, that
would make it rather "easy"or straightforward but this is a halfcircle
(like all test tubes are)!! Answered by Penny Nom. 





A paper tube 
20100221 

From shailesh: How can i estimate weight of paper tube from size. i have paper tube
inner diameter : 22mm, thickness : 2mm, length : 14mm. so how can i got weight
of paper tube? Answered by Harley Weston and Tyler Wood. 





A paper towel roll 
20090819 

From Jeff: I am making a spiral tube with paper that is 2" in dia. and 102" long
I will be using paper that is slit 3" wide how many lineal feet of paper will
I need to to cover the 102"
I will be using 3 rolls of paper that will over lap the other by half to make
a hard tube (paper core) in a roll of paper towels
Thanks Jeff Answered by Penny Nom. 





Measurements on a test tube 
20071030 

From Bruce: I figure that the surface area (SA) of a round bottom test tube
can be determined by the equation SA = 2pi*h*r
where r is the radius of the hemispheric bottom & column part, and
h is the height (h) at any point upwards from the bottommost portion
in the center of the tube.
I haven't been able to come up with an equation yet for the circumference
of such a test tube at any point upwards along the tube based
on the height in its center or on the distance along the outside
of the tube. Answered by Harley Weston. 





20 tubes of concrete 
20071014 

From Fred: I have 20 8” concrete tubes to fill with 8'of concrete.
How much concrete will I need to order Answered by Stephen La Rocque. 





Volume of an inner tube 
20070210 

From Bubba: For a science project, I'm collecting methane gas in an inner tube. In addition to measuring psi of the inner tube, I'd like to calculate the volume of gas collected. What is the formula for or how would I calculate the volume of an inner tube? I appreciate any help you can give me.
Thanks so much. Bubba Answered by Penny Nom. 





Volume of a tube 
20040114 

From Mike: where can you find how to get volume of a tube:
3 in across x 3 inch high
5 in across x 5 inch high
same formula for both. ONE will get the other. Answered by Penny Nom. 

