Process$-$Oriented Problem $08\mathrm{.}001-$ Static and kinetic friction $-$ DEPENDENT MULTI$-$PART PROBLEM $-$

ASSIGN ALL PARTS

NOTE: This is a mult$-$part question. Once an answer is submitted, you will be unable to return to this part.

You and your brother are helping paint a house. To get to the roof of the house to paint the trim, you place a $3\mathrm{.}2$ m

lightweight ladder on the ground and prop it agalnst the house to where it makes a $60$ angle with respect to the

horizontal ground on which it sets. Your $90$ kg brother begins to climb the ladder to paint the trim. He gets to the second

rung of the ladder and then tells you that he has a feeling that if he climbs any further, the ladder will be on the verge of

slipping from its current position. You tell him to stop climbing the ladder at this point and decide to perform a static

analysis on the ladder to see if it will support your brother if he ascends to the third rung or if the ladder should be placed

closer to the wall of the house on which it rests. The center of gravity of your brother can be assumed to be at point $G$ on

the dlagram. The location of your brother and his center of gravity on the diagram is positioned as if he climbed to the

third rung. The coefficlent of static friction between the ladder and the ground at point $A$ is ${}_S=0\mathrm{.}25,$ and the coefficlent

of kinetic friction is ${}_k=0\mathrm{.}20.$ The wall of the house at $B$ is assumed to be a smooth surface.Before performing a static analysis of the ladder, what assumptions can be made about the system? $($Check all that apply.$)$

Check All That Apply

Gravity can be neglected for this problem.

The force of your brother on the ladder would cause the end of the ladder resting on the ground at point $A$ to want to move to the right.

The weight of the ladder can be neglected for this problem.

Under the given conditions, another frictional force will be experienced by the ladder at point $B.$