Question

The tension in the inextensible string using pseudo-force concept is (in N) (Take $g=10m/s^2$)

Answer 1

The given system can be reframed as shown.
Using pseudo-force concept, we have

For $3\text{kg}$ body:
$T=3g+3a\Rightarrow a=\frac{T-3g}{3}$
For $7\text{kg}$ body:
$T+7a=7g\Rightarrow a=\frac{7g-T}{7}$
Hence,
$\frac{T-3g}{3}=\frac{7g-T}{7}$
$\Rightarrow 7T-21g=21g-3T$
$\Rightarrow 10T=42g$
$\Rightarrow T=42\text{N}$