File:Roulette examples.gif
Summary
Description |
English: If you track the position of a point on a curve while it rolls on a second curve, the result is known as a "roulette".
This GIF shows a few famous and simple examples (but there are many other). |
Date | |
Source | https://twitter.com/j_bertolotti/status/1086254369501253632 |
Author | Jacopo Bertolotti |
Permission (Reusing this file) |
https://twitter.com/j_bertolotti/status/1030470604418428929 |
Mathematica 11.0 code
r = 1; y[t_] := -r Sin[t + \[Pi]/2]; x[t_] := r Cos[t + \[Pi]/2] + r t; p1 = Table[ Show[ ParametricPlot[{x[\[Tau]], y[\[Tau]]}, {\[Tau], 0, t}, PlotRange -> {{-r, 4 \[Pi] + r}, {-2 \[Pi] - r, 2 \[Pi] + r}}, Axes -> False, PlotStyle -> {Red}] , Graphics[{Black, Thick, Line[{{-r, -r}, {4 \[Pi] + r, -r}}], Circle[{r t, 0}, r], Red, Disk[{x[t], y[t]}, 0.2]}, PlotRange -> {{-r, 4 \[Pi] + r}, {-2 \[Pi] - r, 2 \[Pi] + r}}] , PlotLabel -> "Circle on line \[Rule] Cycloid", LabelStyle -> {Black, Bold} ] , {t, 0.001, 4 \[Pi], 0.2}]; r = 1; R = 4; x[t_] := (R - r) Cos[t] + r Cos[(R - r)/r (t)]; y[t_] := (R - r) Sin[t] - r Sin[(R - r)/r (t)]; p2 = Table[ Show[ ParametricPlot[{x[\[Tau]], y[\[Tau]]}, {\[Tau], 0, t}, PlotRange -> {{-6, 6}, {-6, 6}}, Axes -> False, PlotStyle -> {Red}] , Graphics[{Black, Thick, Circle[{0, 0}, R], Circle[{(R - r) Cos[t], (R - r) Sin[t]}, r], Red, Disk[{x[t], y[t]}, 0.2]}, PlotRange -> {{-6, 6}, {-6, 6}}] , PlotLabel -> "Circle inside a circle \[Rule] Hypocycloid", LabelStyle -> {Black, Bold} ] , {t, 0.001, 4 \[Pi], 0.1}]; r = 2; R = 4; x[t_] := (R - r) Cos[t] + r Cos[(R - r)/r (t)]; y[t_] := (R - r) Sin[t] - r Sin[(R - r)/r (t)]; p21 = Table[ Show[ ParametricPlot[{x[\[Tau]], y[\[Tau]]}, {\[Tau], 0, t}, PlotRange -> {{-6, 6}, {-6, 6}}, Axes -> False, PlotStyle -> {Red}] , Graphics[{Black, Thick, Circle[{0, 0}, R], Circle[{(R - r) Cos[t], (R - r) Sin[t]}, r], Red, Disk[{x[t], y[t]}, 0.2]}, PlotRange -> {{-6, 6}, {-6, 6}}] , PlotLabel -> "Circle inside a circle (R=2r) \[Rule] Straight line", LabelStyle -> {Black, Bold} ] , {t, 0.001, 4 \[Pi], 0.1}]; R = 4; x[t_] := (R + r) Cos[t] - r Cos[(R + r)/r (t)]; y[t_] := (R + r) Sin[t] - r Sin[(R + r)/r (t)]; p3 = Table[ Show[ ParametricPlot[{x[\[Tau]], y[\[Tau]]}, {\[Tau], 0, t}, PlotRange -> {{-6, 6}, {-6, 6}}, Axes -> False, PlotStyle -> {Red}] , Graphics[{Black, Thick, Circle[{0, 0}, R], Circle[{(R + r) Cos[t], (R + r) Sin[t]}, r], Red, Disk[{x[t], y[t]}, 0.2]}, PlotRange -> {{-6, 6}, {-6, 6}}] , PlotLabel -> "Circle outside a circle \[Rule] Epicycloid", LabelStyle -> {Black, Bold} ] , {t, 0.001, 4 \[Pi], 0.1}]; r = 2; R = 2; x[t_] := (R + r) Cos[t] - r Cos[(R + r)/r (t)]; y[t_] := (R + r) Sin[t] - r Sin[(R + r)/r (t)]; p4 = Table[ Show[ ParametricPlot[{x[\[Tau]], y[\[Tau]]}, {\[Tau], 0, t}, PlotRange -> {{-6, 6}, {-6, 6}}, Axes -> False, PlotStyle -> {Red}] , Graphics[{Black, Thick, Circle[{0, 0}, R], Circle[{(R + r) Cos[t], (R + r) Sin[t]}, r], Red, Disk[{x[t], y[t]}, 0.2]}, PlotRange -> {{-6, 6}, {-6, 6}}] , PlotLabel -> "Circle outside a circle (R=r) \[Rule] Cardioid", LabelStyle -> {Black, Bold} ] , {t, 0.001, 4 \[Pi], 0.1}]; ListAnimate[Join[p1, p2, p21, p3, p4]]
Licensing
I, the copyright holder of this work, hereby publish it under the following license:
![]() ![]() |
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. |
The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
|
![]() |
This file, which was originally posted to
https://twitter.com/j_bertolotti/status/1030470604418428929, was reviewed on 20 January 2019 by reviewer Ronhjones, who confirmed that it was available there under the stated license on that date. |
Category:Animated GIF files
Category:Animated GIF files between 50 MP and 100 MP
Category:Animations of curves
Category:CC-Zero
Category:Files from external sources with reviewed licenses
Category:Hypocycloid
Category:Images with Mathematica source code
Category:Roulettes (curve)
Category:Self-published work
Category:Tusi-couple