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

Parachute and Air Resistance

  1. Sep 17, 2011 #1
    1. The problem statement, all variables and given/known data
    An ideal parachute accelerates all the air it sweeps as it travels, and the air is accelerated from
    0 to the parachute's velocity. Using F = dp/dt calculate the force on an ideal parachute of area A as a function of its velocity and the density of air. Assuming you wouldn't break any limbs if you jumped from 5 feet high without a parachute, this tells you what steady-state velocity you would like your parachute to reach. What diameter a circular parachute you would need? Suppose you weigh 100 kg (including the parachute, a spare, and a video camera to document your jump) and the air density is 1.2 kg/m^3

    2. Relevant equations

    3. The attempt at a solution

    I'm just a little confused about where to start with this one. Any help?
  2. jcsd
  3. Sep 17, 2011 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    What is the change in momentum of the air molecules in 1 sec?
  4. Sep 18, 2011 #3
    I'm not sure. I've been working on this one for a while, but I haven't gotten very far at all. Any help?
  5. Sep 18, 2011 #4


    User Avatar
    Homework Helper

    The question is "What diameter a circular parachute you would need?" So focus on the diameter of the parachute. What does that affect?

    If you prefer, you could think about it a different way: The question says "Using F = dp/dt calculate the force on an ideal parachute..." So what do you need to know in order to calculate that force?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook