Question

Two blocks of mass $8kg$ and $5kg$ are connected by a heavy rope of mass $3kg$. An upward force of $180N$ is applied as shown in the figure. The tension in the string at point $P$ will be :

• A. $60N$
• B. $90N$
• C. $120N$
• D. $150N$

Answer 1

Answer: (B)

$90N$

We have the acceleration of the system as
$a=\frac{F-Mg}{M}=\frac{180-160}{16}=\frac{20}{16}=\frac{5}{4}m/s^2$
Now tension at point P is given as
$T=m(g+a)$
or
$T=8(10+\frac{5}{4})$
Thus, we calculate $T$ as $90N$.