Liquid Pressure on Balloons

The simulation illustrates the hydrostatic principle that liquid pressure at a depth depends on the height of the column above it (p = ρ g h), not on the total amount of liquid or the container’s width. Water of density 1000 kg/m³ exerts a gauge pressure that pushes equally on the rubber balloons at the pipe bottoms.

Two transparent pipes of equal length but different inner diameters are clamped on stands, each closed by an identical elastic balloon. As water is added, the balloons inflate. When the water columns in both pipes reach the same height, the balloons bulge by the same amount, demonstrating that pressure is a function of depth alone. Students can watch how changing the water height alters the balloon’s expansion and compare the effect across the two pipe widths.

By observing the relationship between column height, pressure, and balloon deformation, learners connect the concepts of pressure, force, and area (F = pA). The activity reinforces the idea that a wider pipe carries a larger weight of water but also a larger area, resulting in the same pressure as a narrower pipe at equal height. This reinforces core fluid‑mechanics ideas taught in middle‑school science.