Two masses on springs (harmonic oscillators) move at right angles to one another in the {x,y} plane. [br][br]One mass moves on the X axis: [math]x(t) = A_x Sin(ω_xt)[/math], [br]The second mass moves on the Y axis: [math]y(t) = A_y Sin(ω_yt + ϕ)[/math][br][br]A time axis is perpendicular to the x,y plane[br][br]The point {x(t),y(t),t} traces a curve in the 3D space {x,y,t}.[br][br][i][b]You can vary all the parameters.[br][br]Can you make the projection on the {x,y} plane of the space curve be a circle? an ellipse? a straight line?[br][br]What determines the orientation of the ellipse? the straight line?[br][br][br][br]Right click and hold to "tumble" the 3D view in the right window.[/b][/i]