A block of mass 0.2 kg is suspended from the ceiling by a light...

Let $m_1 = 0.2 \text{ kg}$ be the mass of the upper block and $m_2 = 0.3 \text{ kg}$ be the mass of the lower block.

For the lower block, the forces acting on it are its weight downwards and the tension $T_2$ of the lower string upwards. Since the system is in equilibrium:

$T_2 = m_2 g$

$T_2 = 0.3 \times 10 = 3 \text{ N}$

For the upper block, the forces acting on it are its weight downwards, the tension $T_2$ downwards, and the tension $T_1$ of the upper string upwards. Since it is in equilibrium:

$T_1 = m_1 g + T_2$

$T_1 = 0.2 \times 10 + 3 = 2 + 3 = 5 \text{ N}$

Alternatively, the upper string supports the total mass of both blocks. Thus, the tension in the upper string is:

$T_1 = (m_1 + m_2)g = (0.2 + 0.3) \times 10 = 5 \text{ N}$

The tensions in the upper and lower strings are $5 \text{ N}$ and $3 \text{ N}$, respectively.