# Retracting cylinder: How far does an elevator settle as the passengers enter?

A 2" diameter hydraulic ram piston supports an elevator in a 2 story building. When the elevator car is at the first floor, the piston is fully retracted into the cylinder. The piston extends 15 feet to place the empty car at the second floor. Eight passengers who each weigh exactly 150 lb. enter the car. If the bulk modulus of the hydraulic fluid is 250,000 psi, how far does the elevator settle as the passengers enter?

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#### Solution Preview

This is based on the concept of stress and strain:

Stress = wt of 8 passengers/area of ram =

wt of 8 passengers = 150*8 = 1200 lb

dia of ram = d = 2" = 2/12 ft

area of ram = pi*d^2/4 = 3.1415* (2)^2/4 = 3.1415 ...

#### Solution Summary

The expert determines how far an elevator settles as the passengers enter. The retracting cylinder is given. With clear explanations and calculations, the problem is solved.