Question

Two blocks of mass $M_1 = 20\, kg$ and $M_2 = 12\, kg$ are connected by a metal rod of mass $8\, kg$. The system is pulled vertically up by applying a force of $480\, N$ as shown. The tension at the mid-point of the rod is :

• A. $144\,N$
• B. $96\,N$
• C. $240\,N$
• D. $192\,N$

Answer 1

Answer: (D)

$192\,N$

Answer 2

Acceleration produced in upward direction
$a=\frac{F}{M_{1}+M_{2}+Mass\, of \,metal\, rod}$

$=\frac{480}{20+12+8}=12\,ms^{-2}$

Tension at the mid point

$T=\left(M_{2}+\frac{Mass\, of rod}{2}\right)a$

$= \left(12 + 4\right) \times 12= 192\, N$

$\text{Therefore, the correct option is (D): 192\;N}$