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 "orez" backwards 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

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

Archive

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