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: Egg drop

  1. Nov 21, 2016 #1
    • Member advised to use the homework template for posts in the homework sections of PF.
    For my physics assignment we have to design and test a way to allow an egg to fall from a three storey building and not crack. The only requirments are the egg must be visible in atleast one place and the smallest design wins. I tried making a crumple area and then protecting the egg with ziplock bags full of air but they popped and the egg broke leaving me with few ideas on how to succed. Thank you in advance
  2. jcsd
  3. Nov 21, 2016 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF;
    Parachute? Helium balloon?
    Glue or tape the ziplock bags shut - or use stronger bags - or reinforce the bags with tape?

    Your trouble is not in getting a design that works, it is beating the others to smallest design - without knowing what that will be first.

    How is "smallest" being measured?
    ie. you can pack a parachute into a small volume to deploy when dropped.
    There is also the "Jamie method" - the device is a spool of thread that unwinds on a brake, suspend the egg on the line ... this is very small, but most of the contraption is left behind and the egg is not so much dropped as lowered. You can get out of that by lowering the egg almost all the way and releasing the thread so it drops an inch or so. easy to protect against that right?

    However - there is a limit to how much anyone can help you on this. The point of the exercise is that you should do the experiments to figure it out for yourself (then pay attention to how the others did it after the final test). The process of figuring it out is the point.

    But there is nothing stopping you looking at other people's designs online - there are lots.
    Make sure you understand what they did and vary the design so it is yours.
    Last edited: Nov 21, 2016
  4. Nov 21, 2016 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Good set of ideas from Simon.
    If it really must free fall, no parachute etc., then the trick is to absorb the impact energy over the shortest distance consistent with the max force the egg will take. In particular, it is better to have a constant retarding force than one which increases as the impact progresses (such as would happen with rubber pads, etc.).
    E.g. consider the egg fitting snugly inside a cardboard tube which, somehow, hits the ground vertically with the egg near the top end. The force on the egg as it slides down would be a constant kinetic friction. Might have to encapsulate the egg to spread the force on the bottom half of the shell.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted