Question

A steel wire can withstand a load up to $2940N$. A load of $150kg$ is suspended from a rigid support. The maximum angle through which the wire can be displaced from the mean position, so that the wire does not break when the load passes through the position of equilibrium, is (in degrees):

• A. 30
• B. 60
• C. 80
• D. 85

Answer 1

Answer: (B)

60

$T_{max}=2940N$
Tension will be maximum at bottom because velocity will be maximum.
$T=mg+\frac{m{v}^2}{R}$ (at bottom)
where, $V^2=2gR(1-\cos \theta )$ by Work Energy Theorem
$T=mg+2mg(1-\cos \theta )$
$=3mg-2mg\cos \theta$

$T_{max}=2940,g=9.81$
$\therefore 2940=4414.5-\left(2943\right)\cos \theta$
$\cos \theta =0.50$
$\theta =60$