Dear DrD, thank your for you clear answer! Some background: this is a real life application of a fast spinning centrifuge. G-forces at the outer diameter of the drum are 45000m/s^2, so the liquid will nearly a cylinder. The centrifugal forces 4500x higher than the gravitation, so it is safe to leave it out of the equation for this application. Thanks again, much appreciated!
Guys & Girls, I need your help. Problem is this: Suppose I have a round drum, rotating about its main vertical axis. Top and bottom are closed off. The drum is partially filled with a liquid. How do I calculate the force that the liquid exerts on the top end bottom lid of the drum. Let's ignore gravity. I have attached 2 calculations I did. The picture I found somewhere on the web. Which one of the two is wrong and why? Or are they both wrong??? Looking forward to hear from you!