Free Fall – Motion Detector Sim

Speed

⬆ At the top: v = 0 but a = −g !
The ball stops for an instant, but gravity never turns off — the velocity keeps changing at the same rate.

Strobe / multiflash every s spread flashes sideways in time v & a arrows

Scenarios

Controls

Coordinates:

Initial height above floor/ground: m Initial velocity (): m/s g: At the floor: catch at release height Coefficient of restitution e: Air drag (quadratic, F = kv²) — terminal speed v_t: m/s

Object: Second object B:

Drag: a = −g − (g/v_t²)·v|v|, so speed approaches v_t. Bounces assume a 0.01 s contact, so the a-t spike height is Δv/0.01 s (drawn clipped). Real sonic detectors can’t read closer than ~0.15 m.

Graphs show what the detector / chosen coordinate system reports. Blue = A, orange = B, red = your prediction. Time axis and scales auto-fit the whole run.