http://www.youtube.com/watch?v=5ogwLIPAjKk
You can stop watching at about 1:50.
In this track race, everyone started at different distances. The people who start on the outside, are placed further ahead because they are farther from the center, therefore, they would be at a disadvantage if they started in a straight horizontal line at the start, the people would need to move faster than those people closer to the inner part of the track. The tangential speed is the distance covered per line. This is also known as linear speed. If the racers were to all start in the same line, the runner on the outside would have a faster tangential speed than the racers on the inner part of the track. The rotational speed also plays a key factor in races. Rotational speed is speed measured depending on the number of rotations per time. Therefore, the racers RPM depends on their personal speed not on their distance.
The fundamentals of running comes from physics too. All runners bend their legs when they run because they are moving their legs closer to their axis of rotation (their hips). We know this is important from the property of rotational inertia. Rotational inertia is the property of an object to resist changes in spin or rotation. It is not based upon the mass of an object, rather where that mass is located or how it is distributed (how far it is from the axis of rotation). Therefore, runners bring their mass closer to the axis of rotation to lower their rotational inertia. The farther away from the axis of rotation, the higher rotational inertia an object has.
Well, first off, this is just insanely crazy! Everyone is running so fast, it is really intimidating. Secondly, I thought this was a really good example to use for physics because you could especially see how prominently each racer bent their legs. I also never really thought about the staggered start before until we learned about rotational inertia in physics. It's funny to think about how physics provides an explanation for almost everything, especially sports. Is it more helpful for you to use real life situations instead of small demonstrations with meter sticks and cups?
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