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:
Creative Commons CC-Zero 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.

Category:CC-Zero#Roulette%20examples.gif
Category:Self-published work
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:Files from external sources with reviewed licenses#Roulette%20examples.gif Category:Animations of curves Category:Images with Mathematica source code Category:Animated GIF files Category:Animated GIF files between 50 MP and 100 MP Category:Tusi-couple Category:Hypocycloid Category:Roulettes (curve)
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