Final answer:
A man in static equilibrium with no horizontal force acting would have the vertical forces -- weight and normal force -- balanced. On an inclined plane, gravity's effect is divided into components perpendicular and parallel to the plane, potentially causing motion unless opposed by friction. The concept of force components also extends to the work done in practical scenarios, such as pushing a lawn mower.
Step-by-step explanation:
Understanding Forces and Equilibrium
When considering the movement of a man when the resultant horizontal force is zero, we focus on the vertical forces which are illustrated in a free-body diagram. In a state of static equilibrium, these forces must balance out, leading to no acceleration in any direction. The key forces in this context are the weight of the man acting downwards and the normal force acting upwards with equal magnitude but in the opposite direction to the weight.
When an object is on a non-inclined surface, the normal force is simply the weight of the object because they are equal and opposite.
However, on an inclined plane, gravity's force is resolved into two components: one perpendicular to the plane (w1) and one parallel to the plane (wl). The normal force balances out the perpendicular component, while the parallel component has the potential to cause acceleration down the slope unless opposed by friction.
For example, when pushing a lawn mower, the work done is the product of the force applied and the displacement in the direction of the force, which demonstrates how these concepts translate to practical applications involving work and energy.