$A$ stone is dropped from the top of a tower. Its speed after it has fallen $20 \, m$ is (Take $g = 10 \, m s^{-2}$): (in $, m s^{-1}$)

$A$ body moving with uniform acceleration has velocities $20 \, m/s$ and $30 \, m/s$ when passing two points $A$ and $B$. Then the velocity midway between $A$ and $B$ is:

$A$ train is travelling at a speed of $90\, km \,h^{-1}$. Brakes are applied so as to produce a uniform acceleration of $-0.5\, m s^{-2}$. Find how far (in $m$) the train will go before it is brought to rest.

$A$ trolley,while going down an inclined plane,has an acceleration of $2 \,m \,s^{-2}$. What will be its velocity (in $cm \,s^{-1}$) $3 \,s$ after the start?

$A$ train is travelling at a speed of $90\, km\, h^{-1}$. Brakes are applied so as to produce a uniform acceleration of $-0.5\, m\, s^{-2}$. Find how far the train will go before it is brought to rest. (in $, m$)

Draw a velocity-time graph for a body which starts to move with initial velocity $u$ under a constant acceleration $a$ for time $t$. Using this graph,derive an expression for the distance covered $S$ in time $t$.