1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Multibody dynamics: reverse bungee

  1. Jul 7, 2010 #1
    1. I need to simulate a reverse bungee ejection seat (carnaval ride). This is a vehicle attached to two masts with bungee cords. I know the mass, air drag and acceleration (4.8 g). The first step is to calcutate the spring constants of the bungee cords and the damping constant (relative damping of 10%)

    2. In order to calculate the spring and damping constants I have used: F=m*a. Thus F=400*4.8*9.81. I have used the original length of the ropes to calculate k and used the critical damping (critical damping=2*sqrt(k*m)) to determine c. (c=0.1* critical damping)

    3.The trouble I am encountering is with the movement of the vehicle. The displacement depends on the accelerations, but the acceleration changes over time. For the movement in upward direction I have used the following: F=m*a+Fs+Fd-m*g-D. But there are also rotational forces, becuase the vehicle spins around its y-axis, which causes forces in the z and x-direction.

    Can anyone help me with determining the proper forces?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted