$A$ non-uniform bar of weight $W$ is suspended at rest by two strings of negligible weight as shown in the figure. The angles made by the strings with the vertical are $36.9^{\circ}$ and $53.1^{\circ}$ respectively. The bar is $2 \; m$ long. Calculate the distance $d$ of the centre of gravity of the bar from its left end.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) The free body diagram of the bar is shown in the figure.
Length of the bar,$l = 2 \; m$.
$T_1$ and $T_2$ are the tensions in the left and right strings respectively.
For translational equilibrium in the horizontal direction:
$T_1 \sin 36.9^{\circ} = T_2 \sin 53.1^{\circ}$
$\frac{T_1}{T_2} = \frac{\sin 53.1^{\circ}}{\sin 36.9^{\circ}} = \frac{0.800}{0.600} = \frac{4}{3}$
$\Rightarrow T_1 = \frac{4}{3} T_2$
For rotational equilibrium,taking the torque about the centre of gravity:
$T_1 \cos 36.9^{\circ} \times d = T_2 \cos 53.1^{\circ} \times (2 - d)$
Substituting $T_1 = \frac{4}{3} T_2$:
$(\frac{4}{3} T_2) \times 0.800 \times d = T_2 \times 0.600 \times (2 - d)$
$\frac{3.2}{3} d = 1.2 - 0.6 d$
$1.067 d + 0.6 d = 1.2$
$1.667 d = 1.2$
$d = \frac{1.2}{1.667} \approx 0.72 \; m$.
Thus,the centre of gravity of the bar lies $0.72 \; m$ from its left end.

Explore More

Similar Questions

$A$ small ball of mass $m$ is suspended from the ceiling by a string of length $L$. The ball moves along a horizontal circle with constant angular velocity $\omega$, as shown in the figure. The torque about the centre $(O)$ of the horizontal circle is

$A$ $3\; m$ long ladder weighing $20\; kg$ leans on a frictionless wall. Its feet rest on the floor $1\; m$ from the wall as shown in the figure. Find the reaction forces of the wall and the floor.

$A$ rod of mass $M = 1 \ kg$ and length $L = 1 \ m$ is suspended horizontally by two ideal strings as shown in the figure. The strings are attached at a distance of $1/3 \ m$ from each end. First, a mass $m_1$ is suspended from the left end while keeping the rod horizontal. Then, a second mass $m_2$ is suspended from the right end, again keeping the rod horizontal. What is the maximum total mass $(m_1 + m_2)$ that can be suspended in this way while maintaining the horizontal orientation of the rod?

$A$ uniform meter scale is balanced at the $30 \ cm$ mark on a knife edge,when weights of $60 \ N$ and $10 \ N$ are suspended at the $10 \ cm$ and $80 \ cm$ marks,respectively. The mass of the meter scale is: $(g = 10 \ m/s^2)$ (in $kg$)

$A$ uniform rod $AB$ of length $\ell$ and mass $M$ is suspended from a point at a variable distance $x$ from end $A$,as shown. To keep the rod horizontal,a mass $m$ is suspended from its end $A$. $A$ set of $(m, x)$ values is recorded. The appropriate variables that give a straight line when plotted are:

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo