Bouncing eggs

Subject: Bouncing eggs
From: Richard Jordan <>
Date: Fri, 27 Mar 1998 11:31:42 +1100 (EST)
If you only want to read the serious bird-sighting stuff on birding-aus
activate your message zapper now-----------

For the rest out there I had an almost religious experience yesterday (those
who know me will react with incredulity) . Having breakfast, I was looking
through correspondence from the New Scientist (UK) back in 1960 that
concerned a spate of egg-throwing over houses, and the reasons for some eggs
surviving intact. I imagine that English people (see - I avoided the 'P'
word) have such small gardens that super-house trajectories are necessary to
give the necessary range. Having a box of the appropriate Gallus gallus
product (Large, battery-laid) I went outside and stood at the top of my
grassy hill. I hurled an egg as far as I could at a launch angle of approx
45 degrees. It bounced when it hit the lawn, hit a tree and broke.
Astonished, I tried again with better aim (and a new egg). This time it
bounced to a height of around 30cm and came to rest quite intact. I find
this a mind-blowing illustration of the shock-absorbing properties of the
egg. Light rain meant that the ground was not rock-hard, and the lawn had
not been cut for a month - but even so! Could this have ramifications for
systems for Mars landers, parachute-less aircraft drops I thought? Talk in
the NS indicated that hard-boiled eggs, or those without yolks, broke on
impact - so the presence of the yolk is necessary. The egg must undergo
significant deformation on contact, but commonsense says that this is
impossible without breakage. What is happening? Is it a miracle?

In the NS there was discussion about whether the aerodynamics of the egg
ensured that it landed on the pointy end when thrown far enough. Mine still
seemed to be rotating on impact, but the era of the video camera (not
available in 1960) should help here. I will attempt to film the descent
tomorrow (when I will have a research assistant available) and let you know
the result. 


Richard Jordan 
PO Box 4
Jamberoo, NSW 2533, Australia

phone +61 2 42 360542
fax   +61 2 42 360176

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the birding-aus mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU