Spring constant in an elevator

In summary, to find the spring constant of the springs located under an elevator, you can measure the spring dimensions and use the conservation of energy principle. Note that elevators usually have springs and not shock absorbers. You can also use the maximum g-force a person can bear and the maximum compression of the spring to calculate the spring constant. However, this method may not be accurate as it does not take into account the mass of the elevator and the velocity at which it falls. It is recommended to use an accelerometer to accurately measure the spring constant.
  • #1
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hi,

i am required to find the spring constant of the spring(s) below a typical elevator, you know the big metal springs locater underneath the elevator when it lands on the ground floor right. i have to find the spring constant/stiffness of the springs. anyone knows how to go about doing it w/o tearing up the lift? i know i have to use an accelerometer... thanks for ur help.

serene:bugeye:
 
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  • #2
If you're allowed to measure the compression of the spring, then use the conservation of energy principle.
 
  • #3
Hi serene,
Without tearing up the lift? So I assume you're looking at an existing elevator installation? If so, I'd suggest simply measuring the spring dimensions and calculating the spring constant. I'd assume you're referring to a coil spring, in which case you only need the overall diameter, diameter of the wire used, and number of free turns.

Note that elevators generally have a hydraulic shock absorber of some sort to absorb impact if the elevator drops accidentally. They aren't springs. If they were simply springs, the elevator would be accelerated upward after impact.
 
  • #4
I suppose that you need to find the spring constant to put in an elevator physics problem.
You must know the total kinetic energy that the spring must transform in potential energy. That is what is the kinetic energy [tex]{1 \over 2}mV^2[/tex] that the springs must accept before shortening too much. The kinetic energy depends on the mass of the cabin and the drop height.
The potential energy of a compressed or stretched spring is [tex]{1 \over 2}kL^2[/tex] where k is the spring constant (Newtons/meter) and L is the variation in length of the spring.
This gives you the constant for a single spring. If there are several springs in parallel, the constant is the result obtained divided by the number of springs.

Q_Goest said:
Note that elevators generally have a hydraulic shock absorber of some sort to absorb impact if the elevator drops accidentally. They aren't springs. If they were simply springs, the elevator would be accelerated upward after impact.

All elevators I have seen have springs and not shock absorbers. Have you ever looked inside an elevator duct?
 
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  • #5
ppl.. d problem is simple..
suppose d maximum gforce a person can bear is g(f).
then maximum spring force
kX(m) = m(l) . ( g + g(f) )
where m(l) is mass of lift including mass inside it.X is maximum compression of spring. maximum force is applied at this point according to hooks law.

and energy equation is
1/2 m(l) V(sqr) = 1/2 k X(sqr)
this gives u X. and u know kX. So now u noe K.

V is the velocity d lift falls at. It cn be calculated from d hieght at which it is falling

m(l).g.h = 1/2 m.V(sqr).
 
  • #6
springs are used in some cases ... instead of hydraulic absorbers.
 

1. What is the spring constant in an elevator?

The spring constant in an elevator refers to the stiffness of the spring that is used to support the elevator's weight. It is a measure of how much force is required to stretch or compress the spring by a certain distance.

2. How does the spring constant affect an elevator's movement?

The spring constant plays a crucial role in determining how an elevator moves. If the spring constant is too low, the elevator may feel bouncy and unstable. On the other hand, if the spring constant is too high, the elevator may move slowly and require more energy to operate.

3. Can the spring constant be adjusted in an elevator?

Yes, the spring constant can be adjusted in an elevator. Depending on the type of elevator, the spring constant can be changed by adjusting the tension of the cables or by altering the tension of the springs themselves. This allows for smoother and more efficient elevator movement.

4. How is the spring constant calculated in an elevator?

The spring constant in an elevator is typically calculated by measuring the weight of the elevator and the distance it moves when a certain force is applied. The formula for spring constant is k = F/x, where k is the spring constant, F is the applied force, and x is the distance the spring moves.

5. What happens if the spring constant is too high or too low in an elevator?

If the spring constant is too high, the elevator may require more energy to operate and may move slowly, which can lead to longer wait times for passengers. If the spring constant is too low, the elevator may feel bouncy and unstable, making passengers feel uncomfortable and unsafe.

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