Updated September 2026, 2 weeks ago
Stand-up Maths
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Calculating π by hand
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![How fast is a bullet? [featuring: pendulum calculation]](https://i.ytimg.com/vi/IoYm8lcJQ0o/mqdefault.jpg "How fast is a bullet? [featuring: pendulum calculation]
Thanks to the Cambridge Engineering Department for building the pendulum.
http://www.eng.cam.ac.uk/
Much appreciation to Maria Kettle and Cambridge Engineering Outreach for organising the day.
http://www.eng.cam.ac.uk/events-and-outreach/schools-and-community-outreach
And Hugh was there.
http://www2.eng.cam.ac.uk/~hemh1/
The Cambridge University Rifle Association were super helpful and let us take over their range for most of the day! Katherine Fleck was our expert shooter with infinite patience.
http://cura.soc.srcf.net/
If you have other suggestions for calculating the speed of a bullet: let me know!
CORRECTIONS
- At 3:17 the close-up shows the sliding box already taped to a piece of paper. I only noticed when uploading that we had used this shot from later in the day by accident. It should have been the shot of the box sliding off the pendulum platform. Our solution to fix this problem was to tape it to a piece of paper.
- A few people have asked why we didn’t use a “chronograph”. We did actually use one which detects the movement of the bullet using infrared sensors. But the .22 bullet was too small to trip them.
- People have commented that we didn’t need to use the equation for the period as we know the length of the pendulum and the value of g. But the period is really easy to measure accurately by letting the pendulum swing for ages. Length could be measured fairly accurately (guessing the centre of mass) but g would require an extra assumption.
- Let me know if you spot anything else!
Thanks to my Patreon supports who do support these videos and make them possible. Here is a random subset:
Nicholas Main
Julian Metzler
Amanda Pagul
Christopher Wilson
Claire Greenhalgh
Support my channel and I can make more maths videos:
https://www.patreon.com/standupmaths
Music by Howard Carter
Filming and editing by Trunkman Productions
Sound production by Peter Doggart
Design by Simon Wright
MATT PARKER: Stand-up Mathematician
Website: http://standupmaths.com/
NEW BOOKk: http://wwwh.umble-pi.com
Nerdy maths toys: http://mathsgear.co.uk/")
![The biggest hand calculation in a century! [Pi Day 2024]](https://i.ytimg.com/vi/LIg-6glbLkU/mqdefault.jpg "The biggest hand calculation in a century! [Pi Day 2024]
Please note down the new value of pi: 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223176
If youd like to sign up to hear about future ridiculous maths projects that require volunteers: https://forms.gle/w44THpNJ3jWUPqHy6
Play list of all my previous calculating pi day videos: https://youtube.com/playlist?list=PLhtC92GarkjyYbxI3-4qzIWIRbZaw4wuP&si=DzWXgnv_vYfDgiLZ
This calculation was paid-for with surplus funding from a previous Stand-up Maths kick-starter. If youd like to support future projects, you can join me on Patreon. My Patreon supporters keep me irrational. https://www.patreon.com/standupmaths
Huge thanks to the Pi-by-hand Committee who spent two years working on this project:
Alex Genn-Bash
Ayliean McDonald - https://www.youtube.com/@Ayliean
Ben Sparks - https://www.youtube.com/@SparksMaths
Christian Perfect
Deanna Judd
James Grime - https://www.youtube.com/@singingbanana
Katie Steckles - https://www.youtube.com/@KatieSteckles
Matthew Scroggs - https://www.youtube.com/@chalkdustmag
Max Hughes
Nicole Jacobus
Sophie Maclean - https://bit.ly/Sophie_Numberphile
Thanks to Steve Mould for making sure everything was legit, and only mentioning tau six or so times.
William Shanks was voiced by the excellent Ben Moor: https://www.spesh.com/ben/
The amazing voice over was provided by the fantastic Gemma Arrowsmith: https://www.gemmaarrowsmith.com/
CORRECTIONS
- None yet, let me know if you spot anything (other than the final 6).
- Yes, this video was released the day before Pi Day. Its so teachers have a chance to watch it and prepare their Pi Day lessons for the big day.
Filming and editing by Alex Genn-Bash
Animations by Willow Marler
Written and performed by Matt Parker
Produced by Nicole Jacobus
Music by Howard Carter
Design by Simon Wright and Adam Robinson
MATT PARKER: Stand-up Mathematician
Website: http://standupmaths.com/
NEW BOOK: https://mathsgear.co.uk/products/love-triangle-by-matt-parker-signed")
