Posted by Anonymous on .
A woman is standing on the middle of a ladder that leans up against a building, with an angle of 65 degrees from the ground. The wall is very slippery and the ladder is very light. What is the minimum coefficient of friction needed between the ground and the ladder so that the ladder doesn't fall down?

Phyiscs 
bobpursley,
I bet summing moments around any point will solve this.