Question

How far along the ladder can the man climb before the ladder starts to slip?

• A. $3m$
• B. $5m$
• C. $2.7m$
• D. $1.25m$

Answer 1

The correct option is C $2.7m$

Now, applying the condition of equilibrium-

$\sum F=0N_2=740+160=900N$

Now, $N_1+(-\mu N_2)=0\Rightarrow N_1=0.4\times 900=360N$

Now, $\sum \tau =0$ about point A

$160\times \frac{3}{2}+740\times x=N_1\times 4\Rightarrow 240+740x=1440\Rightarrow x=\frac{1200}{740}=\frac{60}{37}$

Now, $\frac{60}{37\times l}=\frac{3}{5}\Rightarrow l=\frac{300}{11}=2.70$

So, the length of ladder the man climb $=2.7m$