Get 75% off NordVPN with this link: https://nordvpn.com/steve and use the promo code steve to get the first 30 days free.

Quartz watches have a tiny crystal tuning fork inside that vibrates at 2^15 Hz and there's a really clever reason for that. This video also talks a bit about how mechanical watches work.

CORRECTION: Ok, so I actually hung 16 flip flops! So you do need 15. I'm an idiot.

The atomic clock video is here:    • How Do Atomic Clocks Work?  

The piezoelectricity video is here:    • Piezoelectricity  why hitting crysta...  

You can buy my books here:

https://stevemould.com/books

Patreon:   / stevemould  
Twitter:   / moulds  
Instagram:   / stevemouldscience  
Facebook:   / stevemouldscience  
Buy nerdy maths things: http://mathsgear.co.uk