Physics Sim · Sandbox

Changes apply immediately, including while running. Hover a name for details.

Simulation

Snapping (Z) — 0.5 m / 15° Scene boundary walls

Gravity ↓ m/s²

Air resistance s⁻¹

Fields

Electric field → N/C

Electric field ↑ N/C

Magnetic field ⊙ T

Charge interactions

Mutual electric forces

Coulomb constant N·m²/C²

Near-contact smoothing m

Scene

Widthm

Heightm

Bounds stay fixed while you pan or zoom. Ground stays at y = 0. Resizing does not reposition existing objects.

Website

Theme

GUI size100%

Show grid Angle unit Website preferences are remembered on this browser.

Debug · icon preview

Icon set

.: Step one 1/120 s while paused (Step button)
Space: Play / pause. Reset (beside it) returns to the state at load or at the last Run.
Q · Shift: Select tool · add to a selection box
G · B · N · W: Grab · Ball · Block · Wedge
S · D · T · U: Spring · Rod · Belt · Pulley
I · H: Impulse · Pan. Scroll to zoom; middle-drag pans in any tool.
E · M: Electric · Magnetic field. Right-click for shape, size and strength; drag to move, Ctrl to rotate, R to resize.
V · F: Toggle velocity · net force vectors
R + drag: Resize in place (ball diameter; block width / height)
Z: Toggle snapping for all geometry edits (also in Settings)
Shift + drag: Move. A position-locked object moves only while paused.
Ctrl + drag: Rotate around the centre. A rotation-locked object rotates only while paused.
Locked objects: With both locks on, an object ignores dragging while running. Paused, a plain drag moves it and Ctrl-drag rotates it; the locks then hold the new pose.
Alt + drag: Refit rod / cable lengths; combine with Shift to move and change length
Ctrl + R: Browser reload
Click the scene: Closes an open panel or menu (that click does nothing else)
Right-click ground: Floor and wall friction / restitution
Delete · Escape: Delete selection · cancel interaction

Select: enable Bodies and/or Fields in tool settings, drag a box, then drag a selected item to move the connected assembly. Z toggles snapping. Pause to move an assembly containing locked positions. Pins and world anchors move with the layout. Belt: click two balls. Pulley: click endpoint, wheel ball, endpoint. Cable ends can move at any angle and connect to springs. Pulley axles start pinned; unlock position to move them. Select a belt for crossed / driven modes. Select a spring to lock its current angle.