1. Oct 12, 2014

### astrologically

http://ronney.usc.edu/AME101/AME101-F14-PS3.pdf [Broken]

number 1 in the link tyty

Last edited by a moderator: May 7, 2017
2. Oct 12, 2014

### Matterwave

Please use the template provided, and also show what you did to try to solve the problem.

3. Oct 12, 2014

### astrologically

4. Oct 12, 2014

### astrologically

uhh how do i get the template now?

5. Oct 12, 2014

### Matterwave

You can start a new thread in another window and just copy and paste the template over to here.

6. Oct 12, 2014

### astrologically

anyways naming the point of where ladder touching the wall 1 and the part where the ladder touches the ground 2 I have
Fn1 will the wall's force on the ladder and Fn2 will be the ground's force on the ladder. Ffr1 is friction of where 1 is and Ffr2 is friction force of where 2 is.

Sum of Fx= Fn1 - Ffr2=0 Fn1=Ffr2
Sum of Fy=Ffr1+Fn2=0=Ffr1+Fn2-150

then I'm not sure what to do.

7. Oct 12, 2014

### astrologically

hmm i did try your way but it's not giving me the template anymore

8. Oct 12, 2014

### astrologically

ahh found it

1. The problem statement, all variables and given/known data
to find all unknowns.
mu2=0.24
distance from person to 1 is 3ft
distance form person to 2 is 7ft
horizontal distance is 4ft
mg of individual is 150lbf

2. Relevant equations
torque=fd

3. The attempt at a solution
Sum of Fx= Fn1 - Ffr2=0 Fn1=Ffr2
Sum of Fy=Ffr1+Fn2=0=Ffr1+Fn2-150

9. Oct 12, 2014

### Matterwave

EDIT: looks like you found it.

I see that your relevant equations has a torque equation in it, and yet you did not attempt to use it in your solution. Why is that?

10. Oct 12, 2014

### astrologically

oh sorry I did try taking moments in both point 1 and point 2 and turned out with nothing.

Taking moment at point 1.
M1=-(3(150))+Fn2(10)

Taking moment at point 2
M2=-(Fn1(10)+(7(150))

Taking moment at where the person is at
M3=-Fn1(3)+Fn2(7)

From there on I'm not sure what to do

11. Oct 13, 2014

### Matterwave

Your moment equations are incorrect because they don't take into account the angle between the force and the radius displacement. The correct equation for torque is $\vec{\tau}=\vec{r}\times\vec{F}$

Also, at point 1 (and at point 2), there are 2 different forces, the frictional force and the normal force. You have to take both of them into account.