Answer to Question #97870 in Mechanics | Relativity for Benedicta Fosu

Question

1. Briefly explain the following concepts as they pertain to running.
I. At low speeds a runner increases his speed mainly by increasing length of stride.
II. At a certain (high) speed, which differs for different runners, the speed is increased mainly
by an increase of stride frequency.
III. Leg drive and not the length of legs has the greatest importance in lengthening the stride
during fast running.

Answer 1

I. Speed is distance over time. If we increase the distance keeping time the same required for one step, our speed increases.

II. Since we cannot stretch our legs infinitely, only we can do at high speeds is to increase the number of steps we do in some period of time.

III. Long legs can be considered as long levers, so it consumes a lot of energy to stretch them. That is why simply increasing the frequency of steps helps to run faster.