Consider two masses $m_1$ and $m_2$ are connected through a pulley. Mass ' $m_2$ ' stats from rest at height ' $h$ ' and falls down. With what speed it hits the ground? (Assume no friction and massless strings & pulleys)

A block of mass $5 \mathrm{kg}$ is kept against an accelerating wedge with a wedge angle of $45°$ to the horizontal. The co-efficient of friction between the block and the wedge is $\mu =0.4$. What is the minimum absolute value of the acceleration of the wedge to keep the block steady. Assume $g=10 \mathrm{m} {\mathrm{s}}^{-2}$