A basic physics problem consists in analyzing the transfer of fluid between two containers using a siphon. We show that a careful analysis of this situation, using Bernoulli's theorem, leads to conceptual misinterpretations if the fluid viscosity is neglected, as is usually required in the exercises. In this work, besides discussing possible solutions to the problem and identifying the conceptual mistakes involved, we present a model for the correct description of the system, considering energy loss in the siphon.
Bernoulli theorem; energy loss; physics education
