Question

In the following figure, the pulley $P_{1}$ is fixed and the pulley $P_{2}$ is movable If $W_{1} = W_{2} = 100 \,N$, what is the angle $AP_{2}P_{1}$ ? The pulleys are frictionless

• A. $30^{\circ}$
• B. $60^{\circ}$
• C. $90^{\circ}$
• D. $120^{\circ}$

Answer 1

Answer: (D)

$2W\,cos\,\theta=W_{2}$

$\Rightarrow 2\times 100\,cos\,\theta=100$
$\Rightarrow cos\,\theta=\frac{1}{2}$
$\Rightarrow \theta=60^{\circ}$
$=2\theta=120^{\circ}$