Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Determining stiffness during hopping

  1. Feb 25, 2007 #1
    Hello everyone,

    I'm a biomechanist attempting to determine stiffness (K) during a hopping task. Basically we instruct a subject to hop at 2.2Hz on a force plate and determine stiffness of the lower body based on force and time values.

    As you can imagine this is a pretty "loose" transferrance from engineering to biomechanics, and the oscillations are not perfect. :uhh:

    The equation that is then used to determine stiffness is:

    K = Peak Force / Change in Length

    Where Peak force is in the Z axis and the change in length is from 0 (standing still) until peak hopping displacement.

    My question to everyone is:

    Should I use an integration of the force value to determine displacement, which has been recommended by some of the previous literature
    Should I use a projectile motion equation to determine vertical displacement during the hops

    Either way seems like it has some flaws, however I'd like to receive the opinions of others before I make up my mind.

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?