A car is travelling along the road at $8\ ms^{-1}$. It accelerates at $1\ ms^{-2}$ for a distance of $18\ m$. How fast is it then travelling ?

Here given, initial velocity $u=8\ ms^{-1}$

Acceleration $a=1\ ms^{-2}$

Distance $s=18\ m$

Let the final velocity be $v$.

On using the equation of motion $v^2=u^2+2as$

$v^2=8^2+2\times1\times18$

Or $v^2=64+36$

Or $v^2=100$

Or $v=\sqrt{100}$

Or $v=10\ ms^{-1}$

 

Thus, the car is traveling at the speed of $10\ ms^{-1}$.