An object starts from rest and attains a uniform acceleration of $4m{s}^{-2}$. What will be its velocity at the end of half a metre?

The correct option is A

$2m{s}^{-1}$

Given, acceleration $a=4m{s}^{-2}$, initial velocity $u=0m{s}^{-1}$ and distance $s=\frac{1}{2}m$.

Let the final velocity be $v$.

We use the third equation of motion $v^2=u^2+2as$

So, $v^2=0^2+2\times 4\times \frac{1}{2}$

On solving we get $v=2m{s}^{-1}$.

Therefore, its velocity at the end of half a metre is $2m{s}^{-1}$.