# Homework Help: How should I model this?

1. Aug 27, 2006

### opticaltempest

I am trying to model the position of a particle as a function of time. The particle is being modeled in the x-y plane. I will be using Maple 10 to do the regression, graphing, etc.

Here is a movie of the particle in motion. It's actually an ant. I plan on modeling the position of the ant as a function of time in order to estimate the velocity and acceleration of the ant.

http://www.zippyvideos.com/6826494495890326/ant/" [Broken]

I plotted where the ant crosses a vertical line. Each grid is 1cm by 1cm. When the ant crosses a vertical line in the video, I estimated its vertical distance from the 0cm line, noted its exact horizontal distance from the 0cm line, and noted the exact time that frame occurred in the video. Each row in the spreadsheet corresponds to when the ant was on a vertical line.

http://img227.imageshack.us/img227/7903/pointplotwithcoordinatetk5.png [Broken]

http://img135.imageshack.us/img135/3810/dataqq0.jpg [Broken]

1. I am trying to model this as a vector-valued function. Does it need to be modeled as a vector-valued function? I believe I must use a vector-valued function because without using vectors how can I completely describe both the horizontal and vertical motion as a function of time?

2. How do I model a vector-valued function? Should I model the vertical distance from the origin as a function of time in order to get the x-component of the vector? Then model the horizontal distance as a function of time to get the y-component of the vector? Then combine these two to form a r(t)=[x-component function]i+[y-component function]j ?

3. Would a graph of this vector-valued function appear anything like my plotted points?

Thanks

Last edited by a moderator: May 2, 2017
2. Aug 28, 2006

### mezarashi

Yes, I believe you are correct in all your doubts. Where you let r represent the position vector of the particle from 0,0.

r_vector(t) = x(t) i + y(t) j

Differentiating this, you will get the velocity vector. Once more and it will be the acceleration vector.