Corking (popping) can kill you |
 If a greater cross sectional area is suddenly presented to the wind, terminal velocity drops suddenly, and the diver appears to pop upwards like a champaign cork. If some unfortunate is directly above, a collision at up to 100 km/h may be fatal. |
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'Corking' is an example of the difference in the view from frames of reference in relative motion. The observer on the ground (stationary frame) sees the corker decelerate and fall more slowly. Fellow divers see the corker suddenly accelerate vertically and disappear overhead. |