Question

In the figure below, a block of weight 60 N is placed on a rough surface. The coefficient of friction between the block and the surface is 0.5. What should be the weight W such that
the block does not slip on the surface?

• A. $60N$
• B. $\frac{60}{\sqrt{2}}N$
• C. $30N$
• D. $\frac{30}{\sqrt{2}}N$

Answer 1

The correct option is C $30N$

From Lami’s theorem
$\frac{T_1}{sin{135}^{\circ }}=\frac{W}{sin135}\Rightarrow T_1=W$
Also,

$T_1=f_l$
$=0.5\times 60$
$=30N$
$\Rightarrow W=30N$