Pressure

The bricks, the balance and the foam are simulated. Each brick’s mass is exactly 2.00 kg and g is 9.8 N/kg. The depth of a dent is in proportion to the pressure; real foam follows this only roughly. The dents stay while you compare them; real slow foam creeps back over a minute or so. The brick always sits flat on the foam.

The tubes, the liquids and the sensor are simulated. The densities are exact (water 1000, brine 1200 and oil 900 kg/m³) and the liquids do not move, so the reading is exactly ρgh for the depth h of the sensor’s face below the surface. The level in each tube stays the same as the sensor goes in; in a real narrow tube, the rod and the sensor would push the level up a little. The gauge leaves out the pressure of the air on the surface, and a real sensor’s readings would wander by a few hundredths of a kilopascal.

With reduced motion each step happens at once: the bricks and the sensor go straight to their places, the camera cuts to the tubes and each run’s readings appear whole.