Why can't a person just walk or run up a wall? What is keeping them from performing this task? Which formula, would best describe what is going on?
Well, gravity is the answer.
<br>The gravitational force is mg, so, in order to walk up a wall, you would at least need a force bigger than mg upwards (see attached picture).
<br>This force would be provided by the wall, exerting friction on your feet. The friction force is proportional to the force ...
This job articulates premises of gravity.