A stone is thrown with an initial speed of $4.9 \,m/s$ from a bridge in vertically upward direction. It falls down in water after $2 \,sec$. The height of the bridge is……….$m$

Two stones of masses $m_1$ and $m_2$ (such that $m_1 > m_2$ ) are dropped $\Delta t$ time apart from the same height towards the ground. At a later time $t$, the difference in their speed is $\Delta v$ and their mutual separation is $\Delta \varepsilon$. While both stones are in flight

From the top of a tower, a particle is thrown vertically downwards with a velocity of $10\; m/s$. The ratio of the distances, covered by it in the $3^{rd}$ and $2^{nd}$ seconds of the motion is (Take $g = 10\,m/{s^2}$)