Final answer:
The mentioned forces, which include gravitational, magnetic, electric, and inertial forces, have various effects on a 5-meter uniform plank. Friction is considered an external force, and forces F₁ and F₂ are calculated based on maintaining static equilibrium of the system.
Step-by-step explanation:
The forces mentioned in the question can affect the 5-meter uniform plank of mass 100 kilograms in different ways. A gravitational force is an external force caused by the mass of the Earth attracting the mass of the plank, acting towards the center of the Earth. The magnetic and electric forces could potentially act on the plank if it is in a magnetic field or if it has an electric charge and is in an electric field, respectively. The inertial force is not an actual force, but rather a result of Newton's First Law of Motion which is often referred to as inertia, indicating an object's resistance to change in motion.
Friction is an external force that always opposes the motion or attempted motion between two surfaces in contact. The magnitude of the forces F₁ and F₂ needed to carry a plank of wood, with uniform mass distribution and the center of gravity at its center, depends upon the requirements for maintaining static equilibrium, in which the sum of all forces and torques equal zero. For instance, if a person carries a 2-meter plank with one hand pushing down at one end and the other holding it up at 0.5 meters from the end, it results in creating a lever system that needs to be balanced according to the principles described in physics.