Force & Energy Lab

Teacher notes

The cart starts at rest on a horizontal, frictionless 100 m track. Its 1 kg base mass includes its booster; changing booster size changes force only. Thrust is constant until the cart reaches the wall. Cart acceleration is F/m during travel. The booster shuts off at contact. The wall wobble is an energy-scaled visual cue only; Humpty Dumpty rides with the rigid wall and never falls. No crash acceleration or wall-force measurement is reported.

The tower models free fall without air resistance. Its impact-force estimate uses a fixed internal stopping rule: d = 0.30 m, a = v²/(2d), and sand contact force = ma + mg. These assumptions are not student controls or required calculations. All objects share this rule; shape, bounce, and material differences are ignored. Tower stopping acceleration is deliberately absent from student readings and graphs.

The sand meter tracks only the kinetic energy present at first contact, so its final value equals the recorded impact KE. Gravity's small extra contribution during sinking is outside this student meter. Tower falls use real elapsed time and 9.8 m/s² gravity; only the collision is slowed. Crater and debris size are qualitative indicators of impact energy/force, not a calibrated crater law. Drawings are schematic. The two required evidence sets are tower mass and cart energy; exploration trials are retained for graphing and CER evidence. This is an independent instructional simulation, not an official OpenSciEd product.