Simulation of fluid pressure in gas and liquid

Chemistry, Forces, Particle model of matter, Physics, Science

Simulation fluid pressure in gas and liquid

Fluid Pressure is a dual-tab GCSE Physics simulation covering the two main contexts where pressure appears at GCSE level.

Liquid tab shows a glass tank always filled to the top with a pressure sensor on a cable that pupils lower to different depths. Four arrows at the sensor show pressure acting equally in all directions. A live P–h graph updates as pupils change depth (0–4.5 m) or switch between freshwater (1000 kg/m³), seawater (1025 kg/m³), and oil (900 kg/m³). The equation chip shows P_gauge = ρgh and P_total continuously. A 4-step guided lesson walks through depth, density, isotropy, and container shape independence.

Gas tab shows a transparent cylinder with a movable piston held by a retort stand and C-clamp. 24 bouncing particles change speed and colour (blue→red) with temperature. A P–V graph plots the current isotherm against a 300 K reference. Pupils control temperature (100–600 K) and volume (30–100%), with PV/T displayed live to confirm the combined gas law. The 4-step lesson covers the Pressure Law, Boyle’s Law, particle collision explanation, and combined gas law.

Suggested class activity — “Two Laws, One Chip”

Pairs activity, ~20 minutes. Each pair needs one device.

Part A — Liquid (8 min)

  1. Set liquid to water. Record pressure at 1 m, 2 m, 3 m, 4 m. Plot P vs h on mini-whiteboards and identify the gradient (= ρg/1000).
  2. Fix depth at 3 m. Switch through all three liquids and rank by pressure. Ask: why does oil give lower pressure than seawater even at the same depth?
  3. Orbit the camera and sketch what the four arrows show. What does “acts in all directions” mean for a dam or a submarine hull?

Part B — Gas (8 min)

  1. Fix volume at 100%. Raise temperature from 300 K to 600 K. Record P at each 100 K step. Is the relationship linear? (It is — Pressure Law.)
  2. Return temperature to 300 K. Halve the volume to 50%. What happens to pressure? Verify: does PV/T on the chip stay constant?
  3. Watch the particles at 100 K vs 600 K. In one sentence, explain why higher temperature means higher pressure in terms of what the particles are doing.

Whole-class close (4 min) Each pair shares their one-sentence particle explanation. Teacher uses the simulation live to test any edge cases pupils suggest (e.g. “what if we push the piston AND heat the gas?”). Point to the PV/T chip as the class confirms it stays constant regardless of which two variables change.

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