(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

http://img206.imageshack.us/img206/8178/ladderjt1.png [Broken]

A uniform 5.0-kg ladder is leaning against a frictionless vertical wall, with which it makes a 15* angle. The coefficient of friction between ladder and ground is 0.26. Can a 65-kg person climb to the top of the ladder without it slipping? If not, how high can the person climb? If so, how massive a person would make the ladder slip?

2. Relevant equations

[tex]

\begin{gathered}

\sum {\vec \tau } = \vec 0 \hfill \\

\sum {\vec F} = \vec 0 \hfill \\

\end{gathered}

[/tex]

3. The attempt at a solution

So, I choose the end of ladder that is touching the floor to be the axis. Now I want to find the sum of the torques, then set them equal to zero. What I don't quite get in the equation is the sin(90-15) in the first term in the following equation my professor gave me:

[tex]

F_W L\sin (90^ \circ - 15^ \circ ) - M_p gL\sin (15^ \circ ) - M_L g\frac{L}

{2}\sin (15^ \circ ) = 0

[/tex]

sin(90-15)? Technically, it should be the angle between the r and F....but this doesn't make sense to me....or perhaps 15* is meant to be the other angle in the triangle?

If anyone can help, it would be greatly appreciated. Thank you!

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# Ladder - Equilibrium

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