1 physics question?

Question

a 80 kg stuntman falls of a 20m platform ,falls for 18m and lands on a 2m deep foam mat what is the minimum upward force the mat must exert to keep him from hitting the ground

Answer 1

The energy gained by a fall of 22 m is
m*g*h=80*9.8*22

this must be counteracted by the work of the foam
F*2
so
F=80*9.8*22/2

F=8624 N

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