Help with a Physics question please?

Question

A woman is reported to have fallen 144 ft from the 17th floor of a building, landing on a metal ventilator box, which she crushed to a depth of 18 inches. She suffered only minor injuries. Neglecting air resistance, calculate (a) the speed of the woman just before she collided with the ventilator, (b) her acceleration while in contact with the box, and (c) the time it took to crush the box. Then assume that the woman fell on a much “harder” surface which only crushed 2 inches, redo the calculations, and use your answers to explain why the woman was “happy” to land on the ventilator box.

Answer 1

a) using energy
.5*m*v^2=m*g*h
v=sqrt(2*g*h)
v=sqrt(2*32*144)

96 ft per sec at impact

b) the average speed during the crushing was
48 ft/s
the time to travel 1.5 ft at 48 ft/s is
(c) 0.031 seconds
therefore the average acceleration is
0=48-a*0.31
(b) a=1536 m/s^2 or 48 times g

and the 2 inches case has t=0.00347 seconds and
a=13824 or 432 times g

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