Question

What is the final speed of an object that starts from rest and accelerates uniformly at 4.0 meters per second2 over a distance of 8.0 meters? 1. 8.0 m/s 2. 16 m/s 3. 32 m/s 4. 64 m/s

Answer 1

Considering that the acceleration is uniform $a=4 (m/s^2)$ we apply the equation
$v^2=v0^2+2as$
with zero initial speed 
$v^2=2as$
and we obtain the speed
$v^2 =2*8*4 =64 (m/s)^2$
Thus $v=8 (m/s)$