What is the spread in these values?

Question

A human being can survive a feet-first impact at speeds up to roughly 12 m/s (i.e., 27 mi/h) on concrete; 15 m/s (i.e., 34 mi/h) on soil; and 34 m/s (i.e., 75 mi/h) on water. Explain the spread in these values.

Impulse and Momentum
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Answer 1

Think about the deceleration experienced in each of these materials. What g-level would you expect if you hit a brick wall? How would that change if you hit a featherbed?