Science Interviews


Tue, 7th Apr 2015

Eggsperiment 3: An egg in a bottle

Georgia Mills, Naked Scientists

Listen Now    Download as mp3 from the show Egg-cellent Easter Science

This time, amaze your friends and relatives by getting a hard-boiled egg into a Egg bottle small milk bottle without touching it. Be careful though, the results can be explosive, as Georgia Mills and Chris Smith found out...

Georgia -   I'm going to get this egg which is quite a bit bigger than the rim of this milk bottle inside without squishing it.

Chris - Wow! Okay, I will bet you a tenner that you can't do it.

Georgia - Deal!

Chris - Go on then. How are we going to do it?

Georgia - Right. So, if you want to do this at home and win some money off your relatives, all you need is one of the old fashioned milk bottles with the sort of small glass rim at the top. This won't work in a plastic bottle. You need a hardboiled egg and some matches.

Chris - Okay, we now have a hardboiled peeled egg.

Georgia - Right. So, what I'm going to do is I'm going to put the egg down for a second and I'm going to light a match and then I'm going to drop it straight into this glass milk bottle then I'm going to put the egg on top and you'll see what happens.

Chris - Okay, right. So, letís light the match. Ready? [POP] Fantastic! What I will say for you Georgia is the egg is inside the bottle. Itís not very egg-shaped anymore. I would say itís more like scrambled egg but it is in there.

Georgia - I didnít expect that to be honest. (laughing)

Chris -   Okay, so what has happened? How did the egg miraculously get drawn straight into the bottle because literally, we put the egg on the top of the bottle and then there was almost like an explosion and it went straight in.

Georgia - Well, the key was in the matches and what the matches were doing in this milk bottle was heating up the air inside. When air gets hot, it expands. So, what happened there was that this hot air expanding was being pushed out of the bottle. There wasnít enough room for it there anymore. So, the pressure inside was temporarily higher. Now, when we put the egg on top and then the matches went out, the air started to cool down again which means it contracted. As there's now less air in the bottle than there was before, this means that there's really low pressure inside the bottle where the pressure outside of the bottle is the same as normal. So, itís much higher, pushing the egg right into the bottle and then creating this lovely omelette.

Chris - Where is this is sort of relevant because yes, I can understand the principle and itís a useful bit of physics, but is this relevant to everyday life?

Georgia - Outside of winning bets, itís really interesting to think about the amount of air pushing down on us all the time. each square meter has about the equivalent of a double decker bus of air pushing down on it all the time. the atmosphere is extremely heavy.

Chris - Well, Iíll grant you this, Georgia. I think I did sort of lose the bet, but some of the egg did break apart when it exploded on its way and then has landed on the table. So, shall we call it a fiver?

Georgia - Sounds fair to me.


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