Magic Fruits 2

**Follow the load.** Every truss you have ever walked past is asking you a question: which of these members is being pulled apart, and which is being crushed? This app 📱 is built around answering it. Pick a span and you get bare line geometry — no illustration, no decoration, just chords, webs, supports and the loads on them. Before a single number 🔢 appears, you commit: tap 👆 a member once to call it **tension**, twice for **compression**, three times for **zero force**. Then you press LOAD, and the structure judges you instead of a message box. Members you called correctly ignite and are redrawn with their stroke width proportional to the force they actually carry, so the load path appears as thickness. Members you called wrongly buckle sideways or snap at the joint, and the span sags. Nothing tells you that you were wrong ❌ — you watch 👀 it happen. Behind the drill sits a real engine, not a quiz ❓ script: - **Truss solver** — a genuine 2D pin-jointed solver (equilibrium at every joint, solved by Gaussian elimination) with support reactions, determinacy checking and a live redraw as you drag ✋ span, depth and bay count. - **Joint by joint** — the method of joints played back one joint at a time ⏱️, with the force triangle drawn as it resolves and both equilibrium equations written out in real numbers 🔢. - **Section cut** — drag ✋ a cut across the span, move the moment centre to any joint, and watch 👀 the arithmetic rewrite while the answer stays the same. - **Supports and reactions** — swap pin for roller, drag ✋ supports along the chord, see 👀 what each one can and cannot resist, and push the span sideways to prove it. - **Shear and moment** — build 🔨 a beam, add point and distributed loads, and read V and M anywhere along it with the two diagrams live under the deflected shape. - **Buckling** — Euler's critical load against a live curve: drag ✋ a strut longer and watch 👀 its capacity collapse, with end conditions, slenderness and the governing failure mode called out. - **Member sizing** — assign real stock sections, or auto-size the whole truss, and grade every member's utilisation with a slenderness cap on the compression members. - **Determinacy** — add and remove members until 2j = m + r balances, with twelve hand-built challenges and an unstable frame that genuinely wobbles. - **Load cases** — flip between dead, snow, wind, uplift and point loading, predict which members will reverse sign, and see 👀 each member's governing case. Plus a reference library 📚 of 24 truss types with live thumbnails and the story of what each was invented to do, 30 written explanations of the mechanisms behind the answers, a 99-term glossary that cross-links itself, spaced review that brings back exactly the members you keep mis-signing, and a specimen file where you can photograph a real roof truss or footbridge, trace its joints onto the picture and solve that structure — or work on a blank grid, because the camera 📷 is always optional. 174 drill structures across eight load cases. Force in kN, lbf or kgf; length in metres or feet; change it once and every number 🔢 in the app 📱 re-labels itself instantly ⚡. Orange is always tension, blue is always compression, teal always carries nothing — nothing here is coloured for decoration. No accounts, no adverts, no sound. Everything you model stays on your device 📱. ---