In a "worst-case" design scenario, a 2000 kg elevator with broken cables is freely falling from height H when it first contacts a cushioning spring at the bottom of the shaft. The spring is supposed to stop the elevator, compressing d meters as it does so (Figure).
A. In testing the spring a mass of 1000 kg dropped from height H = 1.6 m compresses it by d = 1.5 m. What is the force constant of the spring?
B. If the cables break when the elevator is at height H = 3.2 m above the spring, what would be the maximum compression of the spring? (Ignore air resistance and friction in the elevator guides.)
a) m = 1000 kg F = - kx
h = 1.6 m ma = - kx
x = 1.5 m 1000 (9.8) = -k (1.5)
a = 9.8 m k = -6.53 x 10^3 N