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

Bungee jump -> differential equation -> simulink simulation

  1. Jan 11, 2016 #1
    Hello guys, I found this forum using google because I need help with simulating bungee jump model.
    I've already done that with zero initial values and it looks good but I want it more realistic :
    Let's say L is the lenght of rope so elasticity force starts acting when y=L so logically time should be
    t(L) = sqrt(2*g*L)
    I think that if t >=t(L) all forces should be acting togheter until there is not balance between them..
    Canonical form is : y''(t) = g - B/m*y'(t) - k/m*y(t)
    B - air resistance
    m - jumper weight
    k - elasticity ratio
    I'm including screenshot of model I simulated so far...
    What am I supposed to edit ?
    Thanks for you answers!

    Attached Files:

  2. jcsd
  3. Jan 11, 2016 #2
    + I can't figure out why in some point velocity and acceleration goes below zero... If someone could explain me resp. guide me how to correct it I'd be really glad :)
    Values I used :
    B = 13.08
    m = 80
    k = 2.83
  4. Jan 12, 2016 #3
    Ok I solved it with switch... and btw t(L) = sqrt(2*g*L) this is wrong as there is also air resistance..
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook