Final answer:
The question pertains to the field of physics and involves using statics to calculate the normal and friction forces at the base of a ladder used by a person to access a roof.
Step-by-step explanation:
The question involves calculating the forces at the base of an aluminum ladder that is being used by a person to get onto a roof. The setup includes the ladder, which has a known mass, leaning against a house on a concrete pad, with the base of the ladder at a given distance from the house.
The ladder's contact point with the house is assumed to be frictionless. We are tasked with finding the magnitudes of the normal reaction and friction forces at the ladder's base when the person, who also has a known mass, is standing at a specified distance up the ladder.
To compute these forces, one would use principles from statics, a branch of mechanics in physics. The forces can be found by considering the equilibrium conditions for the ladder, meaning the sum of horizontal forces, the sum of vertical forces, and the sum of moments (or torques) about any point should all be zero. The problem involves considering the weight of the ladder, the weight of the person, and the points at which these weights act on the ladder.