A train travelling at $20\ ms^{-1}$ accelerates at $0.5\ ms^{-2}$ for $30\ s$. How far will it travel in this time ?

Here, initial velocity of the train$=20\ ms^{-1}$

Acceleration $a=0.5\ ms^{-2}$

Time $t=30\ s$

Let $s$ be the displacement.

On using the equation $s=ut+\frac{1}{2}at^2$

$s=20\times30+\frac{1}{2}\times0.5\times30^2$

Or $s=600+225$

Or $s=825\ m$