Matter & Fluids Lab

Everywhere

• Topic tabs (under the title) switch between simulations in this lab. Some topics have smaller buttons under the stage for their screens.
• Teach shows live equations with the current numbers and "What to notice" points. Practice gives a numeric problem and a quiz.
• Move the sliders or tap the chips in the right-hand panel. The readings box updates live.
• Pause / Restart control the animation. Clean view hides everything except the stage, for projecting or recording; press Esc to leave it.
• In Practice, type a number (e.g. 12.5 or 3.2e-10), press Check or Enter. Show it on the stage sets the simulation to that problem.
• Nothing is saved: scores reset when the page is reloaded.

Language

• Choose English or বাংলা once on the home page (top right); every lab then opens in that language — tabs, controls, readings, equations, notes, problems and quizzes.

Stress & strain

• Load a wire: choose the material, the load, the length and the diameter. The stretch is drawn exaggerated; the panel gives σ, ε, ΔL and Y, and tells you whether the wire is still elastic, has yielded, or has snapped.
• Stress–strain curve: drag the slider along the curve past the proportional limit P, the elastic limit E, the yield point Y and the breaking stress U. The specimen on the left necks and breaks, and the dashed red line shows the permanent set you would be left with on unloading.
• Young's modulus compared: the same load on steel, copper, aluminium and rubber — same stress, very different stretch.
• Elastic energy: the triangle under the force–extension graph, W = ½FΔL, and the energy density ½σε = σ²/2Y.

Bulk, shear & Poisson

• Bulk modulus: a cube squeezed from every side, ΔV/V = ΔP/B, with B for water, mercury, glass, copper and steel on a bar chart.
• Rigidity: a block with its base clamped leaning over by the shear strain θ = (F/A)/η.
• Poisson's ratio: a rod that gets longer and thinner at once, with σ between 0 and 0.5 on a ruler.

Surface tension

• Film on a frame: pull the sliding wire; F = 2Tl because the film has two surfaces, and the work you do is T × the new area — surface energy.
• Excess pressure: a drop (2T/r), a soap bubble (4T/r) or an air bubble in liquid, with the p–r hyperbola beside it.
• Angle of contact: water on glass, water on wax, mercury on glass, or set θ yourself; the drop shape and the meniscus in a tube follow.

Capillarity

• Three tubes of radius r/2, r and 2r dipped in water, alcohol, oil or mercury: h = 2T cos θ/(rρg), animated as the liquid climbs (or is pushed down). The h against r view is the hyperbola.

Viscosity

• Layers: a plate dragged over a liquid, the velocity gradient, and F = ηA dv/dx for glycerine, castor oil, honey, olive oil, water and air.
• Falling sphere: weight, upthrust and Stokes' drag on a ball, the v–t curve approaching the terminal velocity vₜ = 2r²(ρ − σ)g/9η, shown in slow motion. The Reynolds number tells you when Stokes' law stops being valid.
• Flow through a tube: Poiseuille's Q = πPr⁴/8ηL, the parabolic velocity profile, and the r⁴ bar chart.

Fluids in motion

• Continuity: A₁v₁ = A₂v₂ — the dots speed up in the narrow part.
• Bernoulli: manometer tubes on the wide and narrow parts; P₁ − P₂ = ½ρ(v₂² − v₁²), the venturi meter.
• Torricelli: a jet from a hole at depth h, v = √(2gh), the range R = 2√(h(H − h)) and where to put the hole for the longest jet.

Full guide with teaching tips: User manual (also as a PDF).