Motion Detector Lab.

On friday we learned and experimented with motion detectors. Jackie, Gemma and I all measured motions together. Something interesting I learned that if you keep a constant, smooth speed, you can have zero accelartation and positive velocity. One struggle our group had was to keep the line smooth, it always would get bumpy or jagged! I learned that accelaration is speeding up and slowing down. I was interested when I found out that if you move toward the motion detectors, the distance is negative, and gave a negative slope. When you walk away from the motion detector, the distance is positive, and gives a positive slope.

One thing that confused me is;
Why does the line stay staight if your not moving at all? Why doesn't it just stop?