Philosophy I / Zeno and Melissus
Practice question · Numerical answer

Achilles runs at 10 metres per second and the tortoise at 1 metre per second with a 100 metre head start. After how many seconds does Achilles draw level?

Hints
  1. Achilles gains on the tortoise at the difference of their speeds.
  2. He must make up 100 m at a closing speed of 9 m/s.
Show the answer

11.11 (answers within ±0.2 count)

Why

The closing speed is 101=910 - 1 = 9 m/s over a 100 m gap, so 100/9=11.11100/9 = 11.11 s. The catch-up happens at a perfectly definite moment. Zeno’s infinite subdivision describes only the time before it.

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