We calculate the parametric curve `{t^2,t}` tangent vector and then calculate the `ArcLength` from `0` to `t0` then we get the point `{0,s[t0]}` in y-axis. ``` c[t_] = {t^2, t}; s[t_] = ArcLength[c[τ], {τ, 0, t}]; t0 = .5; Show[ParametricPlot[c[t], {t, 0, 1}], Graphics[Arrow[{c[t], c[t] + Normalize[c'[t]]}]] /. t -> t0, PlotRange -> All] ``` [![enter image description here][1]][1] After that we translate the curve along the direction`{0, s[t0]} - c[t0]` and then rotate it around `{0,s[t0]}` so that the tangent vector become the new direction `{0,1}` which along y-axis; ``` c[t_] = {t^2, t}; s[t_] = ArcLength[c[τ], {τ, 0, t}]; r[t_, t0_] := RotationTransform[{c'[t0], {0, 1}}, {0, s[t0]}][ c[t] + {0, s[t0]} - c[t0]]; Manipulate[ ParametricPlot[r[t, t0], {t, 0, 1}, AspectRatio -> Automatic, PlotRange -> {{0, 1}, {0, 2}}], {t0, 0, 1}] ``` [![enter image description here][2]][2] # New Edition We general the idea from above to deal with two parametric curves. Here we use `NDSolve` to consider the re-parametric equation, and thanks @Daniel Huber provide `FunctionInterpolation` to increasing the speed. ``` r1[t_] = {1.5 + 1.5 Cos[π - t], Sin[π - t]}; t1 = FunctionInterpolation[ InverseFunction[ NDSolve[{s1'[t] == Norm[r1'[t]], s1[0] == 0}, s1, {t, 0, 100}][[1, 1, 2]]][x], {x, 0, 50}] // Quiet; r2[t_] = {t^2, 3 t}; t2 = FunctionInterpolation[ InverseFunction[ NDSolve[{s2'[t] == Norm[r2'[t]], s2[0] == 0}, s2, {t, 0, 100}][[1, 1, 2]]][x], {x, 0, 50}] // Quiet; Animate[Show[ParametricPlot[{r1[t1[s]], r2[t2[s]]}, {s, 0, 20}], Graphics[Arrow[{r1[t1[s]], r1[t1[s]] + D[r1[t1[s]], s]} /. s -> s0]], Graphics[Arrow[{r2[t2[s]], r2[t2[s]] + D[r2[t2[s]], s]} /. s -> s0]]], {s0, 0, 20}, DefaultDuration -> 10] ``` [![enter image description here][3]][3] ``` r1[t_] = {1.5 + 1.5 Cos[π - t], Sin[π - t]}; t1 = FunctionInterpolation[ InverseFunction[ NDSolve[{s1'[t] == Norm[r1'[t]], s1[0] == 0}, s1, {t, 0, 100}][[1, 1, 2]]][x], {x, 0, 50}] // Quiet; r2[t_] = {t^2, 3 t}; t2 = FunctionInterpolation[ InverseFunction[ NDSolve[{s2'[t] == Norm[r2'[t]], s2[0] == 0}, s2, {t, 0, 100}][[1, 1, 2]]][x], {x, 0, 50}] // Quiet; trans[ss_, ss0_] := RotationTransform[{D[r1[t1[s]], s], D[r2[t2[s]], s]} /. s -> ss0, r2[t2[ss0]]][r1[t1[ss]] + r2[t2[ss0]] - r1[t1[ss0]]]; curves = ParametricPlot[{r1[t1[s]], r2[t2[s]]}, {s, 0, 20}]; Animate[Show[curves, ParametricPlot[trans[ss, ss0], {ss, 0, 3 π}]], {ss0, 0, 20}, DefaultDuration -> 10] ``` [![enter image description here][4]][4] [1]: https://i.sstatic.net/qApaR.png [2]: https://i.sstatic.net/d4VUl.gif [3]: https://i.sstatic.net/CCCCF.gif [4]: https://i.sstatic.net/l2ATs.gif