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Thread: Pogostick: springrate N/mm?

  1. #1 Pogostick: springrate N/mm? 
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    Hi everybody,

    I want to make a new kind of pogostick, this time with wave springs:

    https://www.google.be/search?hl=en&s...mg._-_57ZnE8qE

    I'm 65kg and the wave spring can't be higher than 5 cm. How can I calculate the spring rate (N/mm)? When the springrate is too low, I can't jump. What is the minimum N/mm to jump of the ground?

    Thanks a lot!

    Kind regards.


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  3. #2  
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    When you say it can't be higher than 5 cm, do you mean the overall length is 5 cm, or the compression is 5 cm? I will assume the compression is 5 cm.

    I think the best way to calculate this would be by potential energy. Suppose you want to jump 1 meter high. The gravitational potential energy at the top of your jump is mgh = 65 Kg*9.8 meters/second squared*1 meter = 637 joules. This is the energy that would have to be stored in the spring at its maximum compression.

    The potential energy of a compressed spring is PE=0.5*k*x^2 where k is the spring constant and x is the compression

    k=2*PE*/(x^2)
    Equating the gravitational potential energy and the spring potential energy:
    k=2*637/(.05)=509600 N/m = 509.6 N/mm


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  4. #3  
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    I want to place a "mini-pogostick" under my shoes. That's why I want to have the overall length of the spring as low as possible. Suppose I want to run with the tool at 25km/u. How much N/mm do I need? If I want to place 2 wave springs under my shoes. Can I divide the spring potential energy in 2? Thanks a lot! Kind regards
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  1. Pogostick: springrate N/mm?
    By dirtydiana in forum Physics
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    Last Post: April 23rd, 2013, 02:47 AM
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