Eggsperiment 1: Spinning eggs

How to tell is your egg is boiled or not...
07 April 2015

Interview with 

Georgia Mills, The Naked Scientists


Ever been dared to smash an egg over your head? Georgia Mills showed Kat Broken eggArney a handy trick to find out if the egg is raw or boiled, without getting egg on your face...

Georgia -  This is a way to tell if your egg has been cooked without having to smash it open and potentially get raw egg everywhere.

Kat - So, what have we got here? We've got two eggs on the table. They both look exactly the same. Is one of them cooked and one of them not cooked?

Georgia - One of them has been hardboiled for 6 minutes and the other one is complete fresh from the chicken.

Kat - How do we tell the difference between the two?

Georgia - What I'm going to do is I'm going to spin both eggs around on their sides on the table really quickly. I'm going to put my finger on to stop them and then take it off again straightaway.

Kat - Wow! One of them has stopped dead but one of them readily has started rotating again. So, what's the difference between them?

Georgia - Well, the one that kept moving, that's the raw egg. What happened there is that the liquid inside kept its momentum even when I stopped the shell. When I let go again, the momentum caused friction on the inside of the egg and started it moving again.

Kat - That is pretty cool. I mean, if I ever have an egg-based dilemma in my fridge. But is there anything else that we could use this kind of knowledge for about momentum of fluids?

Georgia - Well, it's interesting because this is exactly what causes you to feel dizzy when you spin around because the liquid in your ear keeps its momentum even after you stop. It's really good to use this for when you're thinking about transporting liquid as well. If you have one big container, the liquid inside will keep its momentum and slush up and down and cause things like Lorries to flip up on their side. But if you have small compartments throughout the lorry, this will not happen so much.

Kat - So, I don't have a handy oil tanker but we do have some eggs and I think I will pick the hardboiled one for my tea.


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