How Do You Calculate the Angle of a Slipping Ladder?

[physicsstudent101]

Homework Statement

A 75 kg man stands on a 8meter 25kg ladder at 6 meters above the bottom when it just starts to slip. Mu(s) is.3. What is the angle of the ladder?

ladder mass=25kg
ladder length=8m
man mass= 75kg
radius of man slipping = 6m
Mu=.3
angle= ?

Homework Equations

F= Mu x Normal force
Torque=rFsintheta
X: P=F(s)=Mu(s) x Normal Force = Mu(s) (Weight of ladder + Weight of man) = Mu(s) (Ladder mass x g + mass man x g)
Y: Normal force = weight of ladder + weight of man
(radius of p)(P)(sin angle)= (radius of ladder)(weight of ladder)(cos theta)+(height of man slipping)(weight of man)(cos theta)

The Attempt at a Solution

not sure where to start... [/B]

 

[phinds]

not sure where to start...

As with ALL such problems, you start with a force vector diagram. That generally clarifies how all the forces interact and gives you a starting point for writing equations.