Question

In the figure given, the system is in equilibrium. What is the maximum value that $W$ can have if the friction force on the $40 N$ block cannot exceed $12.0 N$ ?

• A. 3.45 N
• B. 6.92 N
• C. 10.35 N
• D. 12.32 N

Answer 1

Answer: (B)

For equilibrium at point $p$,

$T_{1}=T \cos 30^{\circ}$ and $T \sin 30^{\circ}=W$
$T_{1}=\mu R=12 N$
$\therefore 12=T \cos 30^{\circ} $
$\Rightarrow T=\frac{12 \times 2}{\sqrt{3}}=\frac{24}{\sqrt{3}}$
$\therefore T_{1} \sin 30^{\circ}=W$
$W=\frac{24}{\sqrt{3}} \times \frac{1}{2}=6.92$