To get up on the roof, a person (mass 70.0 kg) places a 6.00-m aluminum ladder (mass 10.0 kg) against the house on a concrete pad with the base of the ladder 2.00 m from the house. the ladder rests against a plastic rain gutter, which we can assume to be frictionless. the center of mass of the ladder is 2.00 m from the bottom. the person is standing 3.00 m from the bottom. find the friction force on the ladder at its base.