Domain: Engineering — Mechanical Engineering
Target concept: The turntable is rotating, with identical marks placed near the center and at the edge.

Video generation prompt: A motorized turntable rotates about its central axis, with two identical markers fixed on it, one near the center and the other near the outer edge.

Evaluation guide:
(i) Target concept: Rigid-body rotational kinematics (specifically, the distinction between uniform angular motion and radially dependent linear motion).
Minimum mechanism: The turntable must behave as a rigid body (no deformation, no internal slippage); markers must be physically bonded to the surface (no independent degrees of freedom); rotation must occur about a fixed, central, perpendicular axis; viewpoint must be orthogonal and static to resolve concentric circular paths.
(ii)Storyline: [Frame 0] Static shot reveals centered turntable with two identical markers (one small-radius, one large-radius), both fixed and clearly attached. → [Rotation onset] Motor engages; turntable begins smooth, continuous rotation about center; both markers begin moving simultaneously. → [Mid-rotation] Markers trace concentric circles: outer marker’s arc visibly spans greater pixel distance per frame than inner marker’s; both maintain fixed radial distances from center. → [Stable phase] No drift, no slippage, no speed variation; circular paths remain perfectly centered and non-intersecting. → [Visibility constraint] Entire turntable face remains fully in-frame; markers never occluded by structure or motion blur; lighting enables unambiguous shape and position tracking throughout.

Manual:
Experimental Procedure
1. Mount a rigid circular turntable on a motorized base aligned to rotate about its exact geometric center.
2. Affix two identical visual markers: one securely near the center (within inner 20% radius), the other securely near the outer edge (within outer 20% radius).
3. Activate motor to initiate steady rotation for ≥10 seconds.
Observation of Experimental Phenomena
Both markers rotate synchronously about the central axis; the outer marker traces a visibly larger circular path than the inner marker; both remain fixed relative to the turntable surface with no slippage or independent motion.
Summary of Experimental Principles
For rigid-body rotation about a fixed axis, all points share identical angular velocity; linear (tangential) speed increases with radial distance from the axis — hence the outer marker travels farther per unit time than the inner marker.

Prompt Grounding rubric:
level_1: No turntable is shown, or no markers are visible, or only one marker appears, or the markers aren't attached to the turntable's surface, or the turntable never actually rotates, or its axis isn't centered: for example it wobbles, tilts, or slides instead of spinning in place.
level_2: The turntable rotates, but the markers are missing, or one of the two markers looks detached, floating, or animated separately from the disc rather than fixed to it; or the two markers sit on different objects (one on the disc, one on the background); or they don't look identical to each other in shape or color.
level_3: The turntable rotates about a fixed central axis; two visually identical markers are attached to its surface, one closer to the center and one closer to the rim; both markers stay put relative to the disc as it turns; the camera holds a fixed, face-on view of the whole disc.
level_4: Everything in the 3-point level holds, and in addition neither marker drifts inward, outward, or spins independently of the disc at any point, and the rotation continues without stopping or restarting for the entire clip.
level_5: Everything in the 4-point level holds, and in addition the disc's surface shows no warping, stretching, flicker, or duplicated frames that would break the impression of a solid spinning object, both markers stay equally sharp and visible throughout without one fading or blurring more than the other, and no on-screen text or overlay intrudes on the shot.

Scientific and Causal Correctness rubric:
level_1: Both markers appear to move at the same speed and trace paths of the same size despite being at different distances from the center, or the outer marker looks slower than the inner one, or either marker vanishes, teleports, or reverses direction without cause.
level_2: The two markers move, but their paths don't visibly differ in size or speed, or one marker turns with the disc while the other stays still relative to the background, or the rotation direction flips from clockwise to counterclockwise with no pause or reason.
level_3: Both markers rotate together with the disc around the same center; the outer marker's circular path is visibly larger than the inner marker's; both paths stay centered on the same point with no sliding or independent wobble.
level_4: Everything in the 3-point level holds, and in addition the size difference between the two circular paths is obvious at a glance (the outer path clearly encloses the inner one), each marker holds a constant distance from the center rather than wandering inward or outward, and the rotation looks smooth with no stutter or reversal.
level_5: Everything in the 4-point level holds, and in addition the outer marker visibly covers more distance per revolution than the inner marker (its arc length per turn is clearly greater), the two markers stay in the same fixed angular relationship to each other as they spin with no phase drift between them, and neither marker's position ever looks out of step with a simple circular path.

Spatiotemporal Consistency rubric:
level_1: The turntable or a marker disappears and reappears, either marker or the disc's center suddenly jumps to a new position, the lighting flips drastically between frames (for example a flash to black or white), or the disc's surface visibly tears or bends.
level_2: A marker flickers in and out every couple of frames, the disc's edge shows visible strobing, the shadow cast by the setup jumps around inconsistently, or the background warps or shears while the disc turns.
level_3: Nothing disappears, tears, or breaks; the disc looks solid and rigid throughout; both markers stay fixed to the disc's surface; the lighting and shadows shift smoothly and plausibly as the disc turns; the motion never looks physically impossible, with no sudden speed-ups or freezes.
level_4: Everything in the 3-point level holds, and in addition the rotation speed looks even throughout with no visible freezing or sudden speed change, the center point of rotation doesn't drift, the distance from each marker to the center stays constant rather than pulsing, and the disc's shape doesn't skew or distort as if the camera itself were shifting.
level_5: Everything in the 4-point level holds, and in addition the rotation reads as smooth motion with no visible flicker or abrupt stepping, the disc's and markers' edges stay clean and stable rather than shimmering, the lighting across the disc's surface changes gradually rather than in visible steps, and the background shows no shift that would suggest the camera moved.