Domain: Natural Science — Physics
Target concept: Comparison of the Sliding Motion of an Eraser and a Metal Block Down the Same Inclined Plane

Video generation prompt: Two identical inclined planes are placed side by side, with an eraser on the left and a metal block on the right. The angle of inclination of the planes is increased simultaneously, and then both objects are released to slide down at the same time.

Evaluation guide:
(i) Target concept: Relative sliding behavior governed by material-dependent coefficients of static and kinetic friction on identical inclines.
Minimum mechanism: Dry contact between solid objects and rigid plane surfaces; gravitational force component parallel to plane must exceed maximum static friction for motion initiation; subsequent acceleration depends on net force after kinetic friction.
(ii)Storyline: [Frame 0–2] Two identical inclined planes side-by-side, eraser resting on left, metal block on right; both stationary, full contact, no motion. [Frame 3–4] Simultaneous release cue (e.g., hands withdrawing or visual marker), no delay between object disengagement. [Frame 5–10] Continuous downward sliding: metal block advances visibly farther and faster; eraser advances minimally or stops early; both maintain planar contact, no rotation, no detachment; viewpoint remains fixed, full setup remains fully visible throughout.

Manual:
Experimental Procedure
1. Place two identical inclined planes side-by-side.
2. Position an eraser on the upper end of the left plane and a metal block on the upper end of the right plane.
3. Simultaneously increase the inclination angle of both planes to the same degree, then release both objects at the same instant.
Observation of Experimental Phenomena
The metal block slides down its plane faster and farther than the eraser, which moves slowly or barely slides before stopping; both remain in contact with their respective planes without rolling or bouncing.
Summary of Experimental Principles
Static friction is greater for the eraser due to higher coefficient of friction with the plane surface, requiring steeper angle to initiate motion; once moving, kinetic friction remains relatively high, limiting acceleration. The metal block has lower coefficients of static and kinetic friction, so it initiates motion at smaller angles and accelerates more readily under gravity.

Prompt Grounding rubric:
level_1: No inclined plane is visible, or only one appears where two are required; the eraser or the metal block is missing entirely; either object is not resting on a plane surface; or neither object is ever released to slide.
level_2: Both inclined planes and both objects are present, but the setup is wrong in some way: the eraser and metal block are swapped (eraser on the right, block on the left), the two planes are not positioned next to each other, only one object is released while the other stays untouched, or the angle change/release action never happens.
level_3: Two inclined planes of the same base shape stand side by side; the eraser rests on the left plane and the metal block rests on the right plane; both objects are released at the same visible moment; both planes and both objects remain fully inside the frame for the entire clip.
level_4: Everything at the 3-point level holds, and beyond that: the two planes are visually identical in length, width, and tilt angle; the eraser's matte rubber body is clearly distinguishable from the metal block's flat, reflective surface by material and color; nothing (a hand, a label, an extra prop) blocks the view of either plane or object.
level_5: Everything at the 4-point level holds, and further: the camera holds one fixed, front-on framing with no zoom, pan, or perspective drift for the whole clip; the two planes keep the same spacing and tilt from first frame to last; the eraser and metal block keep the same size relative to their planes throughout, so the side-by-side comparison stays legible from start to finish.

Scientific and Causal Correctness rubric:
level_1: Neither the eraser nor the metal block slides; or only one of them moves while the other stays put for no visible reason; or both slide the identical distance at the identical rate, showing no material-dependent difference at all.
level_2: Both objects move, but not straight down their plane's slope (e.g., sideways or upward); or an object's motion is discontinuous, jumping from one spot to another instead of sliding continuously; or the eraser tumbles/rotates rather than sliding flat; or the eraser appears to smear or leave rubber residue on the plane surface.
level_3: Both the eraser and the metal block slide down-slope continuously; the eraser's descent is visibly slower and/or covers less distance than the metal block's; the metal block reaches the bottom of its plane earlier, or travels farther in the same span of time.
level_4: Building on the 3-point description: both objects slide flat against their planes without rolling, tumbling, or bouncing; the speed gap between the eraser and the metal block stays wide or keeps growing through the slide, rather than narrowing or reversing partway through.
level_5: Building on the 4-point description: the eraser's speed looks close to constant and slow, consistent with friction nearly balancing gravity's pull on it, while the metal block visibly speeds up as it descends, consistent with gravity dominating over its lower friction; neither plane vibrates, and no unexplained sticking, jerking, or dust trail interrupts either object's slide.

Spatiotemporal Consistency rubric:
level_1: The eraser, the metal block, or a plane appears or disappears mid-clip; a plane's tilt or position jumps abruptly between frames; the scene's overall illumination changes drastically from one frame to the next; either object changes size or orientation with no physical cause; heavy blur makes it impossible to tell the eraser from the metal block.
level_2: A smaller glitch appears: the eraser or metal block flickers or briefly separates from its plane's surface; a plane's edge jitters between neighboring frames; a shadow appears in some frames and is missing in others; an object's apparent size shifts by a small amount (less than about 10%) between neighboring frames without any cause.
level_3: The eraser stays on the left plane and the metal block stays on the right plane for the whole clip, with neither one jumping to a new location and neither plane warping in shape; shadows keep falling in the same direction throughout, even as their length changes with the objects' motion; both objects slide smoothly, never floating above or sinking into their plane's surface.
level_4: In addition to the 3-point criteria: both plane edges stay straight and aligned across the whole clip; the eraser and metal block keep full, flush contact with their plane's surface the entire time, with no lifting, tipping, or rocking; any camera movement never makes an object appear to separate from its plane.
level_5: In addition to the 4-point criteria: each plane's tilt angle and the spacing between the two planes stay visibly constant from the first frame to the last; both objects travel in a straight line down their plane's slope with no zig-zag or sideways drift; the whole slide plays out smoothly, with no sudden position skips or camera shake breaking the comparison.