Awoman 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 18.0 in. she suffered only minor injuries. neglecting air resistance, calculate (a) the speed of the woman just before she collided with the ventilator, (b) her average acceleration while in contact with the box, and (c) the time it took to crush the box.

(a) 96 ft/s

(b) - 3072 ft/s^2

(c) 0.03125 s

Explanation:

h = 144 ft

u = 0 ft/s

g = 32 ft/s^2

(a) let she strikes the box with velocity v.

Use third equation of motion

v = 96 ft/s

(b) Let the average acceleration is a.

initial velocity, u = 96 ft/s

final velocity, v = 0

h = 18 in = 1.5 ft

Use third equation of motion

a = - 3072 ft/s^2

(c) Let the time taken is t.

Use first equation of motion

v = u + at

0 = 96 - 3072 x t

t = 0.03125 second