mscroggs.co.uk
mscroggs.co.uk

subscribe

Blog

New machine unfriendly £1 coin

 2014-03-19 
Vending machines identify coins by measuring their width. Circular coins have the same width in every direction, so designers of vending machines do not need to worry about incorrectly rotated coins causing a blockage or being misidentified. But what about seven-sided 20p and 50p coins?
Perhaps surprisingly, 20p and 50p coins also have a constant width, as show by this video. In fact, the sides of any regular shape with an odd number of sides can be curved to give the shape a constant width.
3, 5, 7 and 9 sided shapes of constant width.
Today, a new 12-sided £1 coin was unveiled. One reason for the number of sides was to make the coin easily identified by touch. However, as only polygons with an odd number of sides can be made into shapes of constant width, this new coin will have a different width when measured corner to corner or side to side. This could lead to vending machines not recognising coins unless a new mechanism is added to correctly align the coin before measuring.
Perhaps an 11-sided or 13-sided design would be a better idea, as this would be easily distinguishable from other coins by touch which being a constant width to allow machines to identify it.
                        
(Click on one of these icons to react to this blog post)

You might also enjoy...

Comments

Comments in green were written by me. Comments in blue were not written by me.
 Add a Comment 


I will only use your email address to reply to your comment (if a reply is needed).

Allowed HTML tags: <br> <a> <small> <b> <i> <s> <sup> <sub> <u> <spoiler> <ul> <ol> <li> <logo>
To prove you are not a spam bot, please type "width" in the box below (case sensitive):

Archive

Show me a random blog post
 2024 

Feb 2024

Zines, pt. 2

Jan 2024

Christmas (2023) is over
 2023 
▼ show ▼
 2022 
▼ show ▼
 2021 
▼ show ▼
 2020 
▼ show ▼
 2019 
▼ show ▼
 2018 
▼ show ▼
 2017 
▼ show ▼
 2016 
▼ show ▼
 2015 
▼ show ▼
 2014 
▼ show ▼
 2013 
▼ show ▼
 2012 
▼ show ▼

Tags

go computational complexity zines fonts london underground logo light london runge's phenomenon bubble bobble edinburgh rugby pascal's triangle talking maths in public preconditioning estimation folding paper misleading statistics books braiding matt parker error bars arithmetic chalkdust magazine sorting national lottery recursion mathsjam gaussian elimination golden spiral statistics cross stitch simultaneous equations mathslogicbot hats geogebra geometry video games mathsteroids realhats reddit martin gardner squares christmas card the aperiodical rhombicuboctahedron sport crossnumber phd folding tube maps latex people maths hannah fry ucl dataset radio 4 dragon curves quadrilaterals determinants weak imposition stirling numbers finite group trigonometry php game show probability approximation python plastic ratio asteroids frobel youtube captain scarlet mean triangles graphs coins european cup flexagons matrix multiplication dinosaurs ternary accuracy matrix of cofactors propositional calculus game of life 24 hour maths speed platonic solids raspberry pi javascript exponential growth pi approximation day news binary christmas datasaurus dozen logic sobolev spaces guest posts standard deviation data visualisation reuleaux polygons hyperbolic surfaces puzzles world cup graph theory fence posts manchester machine learning programming fractals anscombe's quartet royal baby countdown inverse matrices chebyshev wave scattering dates chess electromagnetic field menace matrix of minors manchester science festival noughts and crosses a gamut of games cambridge hexapawn pac-man big internet math-off draughts tennis curvature gerry anderson gather town convergence football newcastle oeis polynomials pythagoras probability crochet databet logs sound harriss spiral numbers craft bodmas golden ratio errors tmip games palindromes inline code map projections royal institution correlation numerical analysis bempp wool nine men's morris advent calendar pizza cutting turtles boundary element methods final fantasy weather station live stream pi data finite element method stickers matrices interpolation signorini conditions

Archive

Show me a random blog post
▼ show ▼
© Matthew Scroggs 2012–2024