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The cable of the 1800 kg elevator snaps when the elevator is at rest at the first floor, where the cab bottom is a distance d = 3.7 m above a cushioning spring whose spring constant is k = 0.15 MN/m. A safety device clamps the elevator against guide rails so that a constant frictional force of 4.4 kN opposes the motion of the elevator.

(image attached - i don't know how to make it embedded, sorry)

(a) Find the speed of the elevator just before it hits the spring._____ m/s

(b) Find the maximum distance x that the spring is compressed.______ m

(c) Find the distance that the elevator will bounce back up the shaft._____m

(d) Using conservation of energy, find the approximate total distance that the elevator will move before coming to rest._____m

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alrite let's see....

a) i've gotten the first answer by dKinetic + dPotGrav (or Ug) + E thermal (from friction) = 0 from conservation of energy.... solve for V final from the kinetic part... 7.37ms-1

b) i believe it should be -1/2mv^2 - mgS + 1/2kS^2 + F(of friction)*S = 0 but i'm not sure if I'm getting the signs wrong... should my answer be negative because its compressing or not?.... not getting the right answer... help please!!!!

c) now i need my result from b) as x and is it 1/2kx^2 = mg(d up) + Friction(s +d up) solve for (d up).... Note: not sure if should just use answer from b) times the friction force or is it friction * (d up)... instead of what my equation says....?????

d) to be honest i'm sorry but i have no clue to this one... and without b) and c)... i'm having trouble understanding it...

i hope some1 can help me out???!!! thanx in advance!!!

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# Homework Help: Elevator problem - help

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