Question

An apple is falling down from a height of 20m and then hit a

person. Assume that the mass of the apple is 200g. The

duration of impact is 0.001 sec and that the area of the

bone is 1 cm(square). (a) Calculate the impulsive force applied to

the person. (b) If the rupture strength for body tissue is

about 5 X 1000000dyn/cm(sqare), will the impact force lead to serious

injury for the person?

Answer 1

a)

$F=\frac pt=\frac {mv}t=\frac mt\sqrt{2gh}=4000~N,$

b)

$\frac FS=4000>\sigma =50,$

the impact force will lead to serious injury for the person.