r/MathHelp • u/Efficient_Fruit7088 • 9h ago
Trouble integrating to find entire volume of horizontal cylindrical tank
I'm trying to solve a problem my class was given for homework - wherein we have to find the volume of fluid occupying a horizontal cylindrical tank at 100%, 90% and 80% capacity.
Since the hemispherical end caps of the tank are segments of a sphere, I reasoned that I'd have to try and build an expression to integrate with respect to the height of the tank.
The issue is, it's been a while since I've learned integrals, especially problems where I have to triple integrate and take weird boundaries.
I've also been given limited information, as I only have the
- straight length (6000mm)
- length running down the segment radius of the tank (2100mm)
- depth of the segment (x = 145mm)
My attempts so far:
Attempt #1: Try and 'brute force' it - by ignoring the end caps initially, finding the volume of the central cylinder at 100% full. Based on the height of the fluid, I tried working with the ratio of full/empty space in the tank and attempted to use simple arithmetic to work out the remaining volume within the tank occupied by fluid. This effort failed.
Attempt #2: I tried triple integrating with respect to cylindrical coordinates (x,y,z) but got very confused as to how to find the radius of the sphere the segment is a part of.
Attempt #3: Followed some YouTube videos and tried to integrate with spherical coordinates (rho,theta,psi) but got confused again - as I was unsure of how to take my boundaries, since I'm unsure as to if I'm supposed to take my reference point as the centre of the sphere or shift it downward. And after that point I'm just not sure how to proceed.
Any help or advice would be really appreciated.
Thanks in advanced!! :)