The discussion centers on why the pressure difference at points 1 and 2 is ignored in the energy equation for incompressible fluid flow. It is clarified that pressure and energy are dimensionally different, and the author assumes equal pressure at both points due to their selection being on the surface, where pressure remains constant. The potential energy terms are highlighted as being divided by ρg, leading to the omission of pressure in the calculations. If points were chosen at different heights, the pressures would differ, but the outcome of the equation would remain unchanged. This explanation underscores the assumptions made in applying Bernoulli's equation in this context.
