# A Displacement graph of an orbiting body

1. Sep 30, 2016

### SirJuantum

If I were to draw a displacement time graph of an arm rotating around it's origin at a constant radius meaning it is a constant displacement from the origin. Meaning the graph looks the same as one of an item that is not moving,how would you draw the displacement time graph of something moving in a circle around the origin

2. Sep 30, 2016

### BvU

Hello Sir J,

You plot the x-coordinate as a function of time, and you plot the y-coordinate as a function of time !
If it starts at $(x,y) = (R,0)$ and turns counter-clockwise, the one is $R\cos\omega t$ and the other is $R\sin\omega t$

 I hope this animation doesn't confuse you too much ... ? Or this

Note that this is not correct: displacement is a vector with an x-coordinate and a y-coordinate in your case. The distance from the origin (the length of the vector) is constant, but not the orientation. In fact you could also plot your arm motion by plotting the angle as a function of time, something like $\phi = \omega t$ -- so pretty boring...

Last edited: Sep 30, 2016
3. Oct 4, 2016

### SirJuantum

YeS this cleared it up completely thank you:D it was just a curiosity I made and I see the error with the scalar and vector quantities