Question

Two blocks of mass $3\text{kg}$ and $2\text{kg}$ are tied by a massless string. A force of $100\text{N}$ is applied on $3\text{kg}$ block as shown. Find the tension in the string. $(g=10{\text{m/s}}^2)$

• A. $20\text{N}$
• B. $40\text{N}$
• C. $80\text{N}$
• D. $160\text{N}$

Answer 1

The correct option is B $40\text{N}$

As the two blocks are moving with same acceleration we can consider them a system of mass $5\text{kg}$.

$100-Mg=Ma$
$100-50=5a$
$a=10{\text{m/s}}^2$
From the F.B.D of $2\text{kg}$ mass,
Using Newton's second law,
$T-m_{2}g=m_{2}a$
$T-20=2\times 10$
$T=40\text{N}$