Question

a girl that has a mass of 55kg is standing on a floor, how much supporting force does the floor have?

Answer 1

A girl standing on a floor would have two opposite forces acting on it. These forces are the weight and the normal force. Since no other forces are acting and that the girl is at rest, then the weight must equate to the normal force. Therefore, the supporting force would be:

F = mg = 55kg (9.81 m/s^2) = 539.55 N