A house painter stands 3 m above the ground on a 4.9-m-long ladder that leans ag

Question

A house painter stands 3 m above the ground on a 4.9-m-long ladder that leans against the wall at a point 4.7 m above the ground. The painter weighs 667 N and the ladder weighs 155 N. Assuming no friction between the house and the upper end of the ladder, find the force of friction that the driveway exerts on the bottom of the ladder.

Explanation / Answer

sin ? = 4.7/5.1 => ? = 67.156 ° and cos ? = 0.3882 Normal at the wall = friction at the floor = F Normal at the floor = 635 + 145 = 780 N 145 N has a horizontal distance of (5.1/2) cos ? = 0.9899m 635 N has a horizontal distance of [ 3 /tan ?] = 1.2637m Taking moment about the point where the ladder rests on the floor F*4.7 = 145*0.9899 + 635*1.2637 F = 201.3 N

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