#$&*
course Phy 231
2/2 3pm
This animation is very helpful to my visualization of acceleration, particularly negative acceleration. After playing around for a bit, I decided to try to set it up so he moved from position -10.0m to +10.0m, decelerating steadily until-- if I could time it right-- he reached a velocity of 0 at precisely the moment he reached position +10.0m.
This proved incredibly difficult! I tried with quite high velocities and significant deceleration, and also lower initial velocities and only slight deceleration. It became clear that even slight changes in rate of change of speed could make enormous differences in the distance the man traveled before coming to rest and reversing direction.
Eventually I realized that my mental calculations were very wrong based on the fact that I was thinking about full seconds as having a steady velocity throughout that entire second. In other words, if I set initial velocity at 10.0m/s, I expected that he would travel 10 full meters in the first second, and then decelerate to some slower rate of speed for the entire NEXT second.
But, a starting velocity of 10.0m/s with an acceleration of -1.03 m/s^2 got him just over 9.1 meters in the first second. I realize now that only at the very instant he began was the man travelling 10m/s for that instant. The very next instant, his average velocity was already less than 10m/s.
This points to the importance of finding average velocity based on the midpoint of an interval, as we did with the rotating strap experiment.
Incidentally, the closest I could get was to start at 5.6m/s with an acceleration of -.8m/s^2. He came to rest at 9.6m."
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You learned some important things. Excellent.
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