Question

Block $A$ of weight $100N$ rests on a frictionless inclined plane of slope angle $30^{°}$ as shown in the figure. A flexible cord attached to $A$ passes over a frictionless pulley and is connected to block $B$ of weight $W$. Find the weight $W$ for which the system is in equilibrium.

• A. $25N$
• B. $50N$
• C. $75N$
• D. $100N$

Answer 1

Answer: (B)

As the system is in equilibrium,
$\therefore$ $T=W$ $\dots \left(i\right)$
and $T=mg$ $sin30^{\circ }$ $\dots \left(ii\right)$
From (i) and (ii), we get

$W=mgsin$ $30^{\circ }=\left(100N\right)$ $\times \frac{1}{2}=50N$