Question

Two blocks of mass $M_1=20\text{kg}$ and $M_2=12\text{kg}$ are connected by a metal rod of mass $8\text{kg}$. The system is pulled vertically up by applying a force of $480\text{N}$ as shown. The tension at the mid-point of the rod is: (Taking $g=10{\text{m/s}}^2$ )

• A. $144\text{N}$
• B. $96\text{N}$
• C. $240\text{N}$
• D. $192\text{N}$

Answer 1

The correct option is D $192\text{N}$


FBD of system


$\Rightarrow 480-400=40\text{a}$
$\Rightarrow \text{a}=2{\text{m/s}}^2$
Now at midpoint



$F_{\text{net}}\Rightarrow 480-24\text{g}-T=24\text{a}$
$480-240-T=48$
$T=240-48=192\text{N}$