Question

Two block each of mass $3.0kg$, are connected by a light cord and placed on a rough horizontal surface. When a horizontal force of $20N$ is applied on a block, an acceleration of $0.50{ms}^{-2}$ is produced in each block. Find the tension in the string and the frictional force which is same on the two blocks.

Answer 1

Taking whole as a system-
$20-2f=6\times a$
$a=0.5m/s^2$
$2f=20-6\times 0.5$
$f=\frac{17}{2}=8.5N$ $\to$ friction force on each block
On block B:-
$T-F=3\times a$
$T=3\times 0.5+F$
$1.5+8.5$
$T=10N$