# “Moving” plot of a point moving in circular motion, in 3D

Maybe this is a tricky one! I want to have a 3D plot in Cartesian coordinates of a point moving in a circular orbit around x,y,z = 0. where the circular motion is only in the x,y plane.

Has anyone any experience with this. I initially started with just plotting a circle on the x,y plane in a 3D axis - but I would like this to be more dynamic!

Thanks!

## 1 Answer

path[var_] = {Cos@var, Sin@var, Sin[4 var]};
Animate[
Show[
ParametricPlot3D[path@u, {u, 0, 2 Pi}, PlotStyle -> Gray],
Graphics3D[{Red, PointSize[0.05], Point[path@v]}],
Graphics3D[Text[ToString@path@v, {0.8, -1.6, -1}]]],
{v, 0, 2 Pi}
]

• Thanks! This is great! Do you know if there is a way I can express this in terms of x,y,z? – Q.P. Mar 5 '16 at 18:29
• Is this what you meant by x,y,z? – thedude Mar 5 '16 at 18:38
• Sorry I know I asked this in a strange way. The reason is I now want to make the particle move up and down in the z-axis while its also moving in a circular motion like you did for me – Q.P. Mar 5 '16 at 18:43
• What about this? Generalized for any parametric path where $v$ is time. – thedude Mar 5 '16 at 18:48
• Very very close! I mean imagine you draw a Sin wave on a piece of transparent paper, and then roll that into a tube...if you see what i mean! – Q.P. Mar 5 '16 at 18:53