Motion Tracking

Finding position as a function of time

Suppose a particle goes from x₁ to x₃ and then back to x₂ at times t₁, t₂ and t₃ respectively. (figure 1)

We can plot where the particle is at different times on a graph (figure 2).

If we also measure the position of the particle at many intermediate times, we can fill in this curve, referred to x(t) – x as a function of time. (figure 3)

Following are some examples:







1) This is a straight line plot – in any time period Deltat, the Deltax is proportional to Deltat. v= Deltax/Deltat is positive with a constant value.

2) This plot also shows a particle with a positive constant velocity. However, because this plot has a steeper slope, the particle has a higher velocity – it is going faster.


3) This plot has a downwards slope – it describes a particle moving in the negative direction.


4) This plot is horizontal. The particle it describes is not moving at all.