Question

In the arrangement shown in figure. The strings are light and inextensible. The surface over which blocks are placed is smooth. What is the tension in the left string. (g= $10m/s^2$).

• A. $12N$
• B. $10N$
• C. $8N$
• D. $6N$

Answer 1

The correct option is C $8N$

Total mass of the system $m_1$ $m_2$, $m_3$ is $m=1+2+4=7kg$

When the system is pulling with a force of $14N$ then the acceleration of the system is $a=\frac{F}{m}=\frac{14}{7}=2m{s}^{-2}$

Now tension in the left string is: $ma=4\times 2=8N$