Pulley & Constraint Motion Simulation Lab

Pulley problems are where JEE students most often memorise instead of reason: "a movable pulley halves the speed" is true only for vertical runs and a fixed anchor. This lab removes the memorising. Its engine measures every string from the actual geometry — the straight tangent runs between pulleys and the arcs it wraps — and differentiates that length, so the constraint for any arrangement, including diagonal strings, pulleys bolted to moving wedges and platforms, and several independent strings, comes out with the right coefficients.

The fifteen modules move from the Atwood machine and a single movable pulley, through the classic figures (a truck pulling a block over pulleys, a stepped block with wall pulleys, a wedge carrying a pulley, a wedge chain), to a tiny-displacement builder, an editor for building your own system, a JEE Advanced challenge lab, pulleys that turn and strings that slip, and a side-by-side comparison of when tensions are equal. Every simulation can be released under gravity, scrubbed in time and viewed in 3D.