What you need

Vernier LabQuest Mini (or LabQuest 2 or 3) connected by USB. Motion Detector in the DIG 1 port, with its sensitivity switch on the cart setting. Chrome or Edge. Other web browsers are not supported.

Put the detector at the high end of the track, aimed along it at the cart. Keep the cart at least 0.2 m from the detector, since it cannot see anything closer than 0.15 m. Distance from the detector grows as the cart rolls down, so down the ramp is the positive direction and the acceleration comes out positive.

If the distances it reports do not match a tape measure, use Calibrate detector once the detector is connected.

Taking a run

1. Hold the cart still at the release mark and press Collect (or Space).
2. Let go without pushing. Catch the cart before it reaches the end of the track.
3. Press Stop. The run appears on both graphs and in the table.
4. Drag the dashed handles so the fit covers only the free acceleration. Do not include any interval in which the velocity is changing unexpectedly.