mariuscomper.uk Metrology
How quickly do you notice movement?

The Falling Ruler: Can you catch it in mid-air?

A 30-centimetre ruler falls in a simulation. Press when you see it move: the interval until your press is converted into free-fall distance. The result includes your response and device delays.

Attempt 1 of 5
Ready to launch
Datum zero (pinch line)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Press the Space bar or tap the screen the instant you see the ruler start to move.

Catch distance
-- cm
Reaction time
-- ms
Kinematic formula
d = ½ g t²

Your 5-attempt series

  • Attempt 1
    --
    Pending
  • Attempt 2
    --
    Pending
  • Attempt 3
    --
    Pending
  • Attempt 4
    --
    Pending
  • Attempt 5
    --
    Pending

Completed Series Summary

Mean and spread describe successful catches.

Average distance
--
Average time
--
Best catch
--
Spread
--

From vision to movement: a simplified outline

  • Vision Retina and optic nerve: Light is detected by photoreceptors. Retinal circuits pass the signal to ganglion cells, whose axons form the optic nerve.
  • Preparation Visual cortex and motor decision: The visual cortex processes incoming information, while motor areas help prepare and execute voluntary movement.
  • Motor signal Spinal cord transmission: The efferent motor signal travels down the corticospinal tract to cervical motor neurons.
  • Movement Neuromuscular junction & contraction: Acetylcholine release depolarizes finger flexor muscles, developing physical clamping force.

What this simulation measures

In a physical ruler-drop test, the distance depends on the visual response and finger closure. Here you press a key or screen, and distance is calculated from the recorded interval. The two procedures involve different movements and delays.

The model uses standard gravitational acceleration, 9.80665 metres per second squared, and d = ½gt². At 100 milliseconds the distance is about 4.9 centimetres; at 200 milliseconds it is about 19.6 centimetres.

Comparing series

Use the same device and input method. Practice, attention and anticipation can change the result. The catch average and miss count describe the series together; a small average from a few catches does not summarize all five attempts.

About the measurement: Scores include display and input-device delays. A very small result can have several explanations, including anticipation; this page cannot determine the cause from that number alone.

Sources and scope: Del Rossi, Malaguti and Del Rossi (2014) studied practice effects in a physical ruler-drop test with 43 participants and observed improvement with repetition. Kadota and Gomi (2010) studied corrections during arm movements, a different task from catching a ruler. Neither protocol validates a universal biological cutoff for this simulation.