Question

The magnitude of Flim between contacting surfaces is frequently of great importance in athletic activities. Excluding footwear changes and playing surface characteristics, , provide two examples in which an athlete attempts to manipulate friction (either increase or decrease) to his or her advantage and describe what the athlete does to affect friction (i.e., provide an indication whether change in the coefficient of friction or the normal reaction force is primarily responsible for the observed change).

Answer 1

An athlete always balance his body with some forward inclination(let theta) about vertical axis(normal to the surface). In this case normal force balanced by vertical component of the given force to surface & weight of the athlete. And its horizontal component is balanced by the frictional force. That's why the athlete never fall whiling running.