Question

A body moving along a straight line at 20m/s undergoes a acceleration of 4m/s2. after 2 seconds what will be its speed and also find its displacement

Answer 1

$s = ut + \frac{1}{2} {at}^{2} \\ s = 0 \times2 + \frac{1}{2} 4 \times {2}^{2} \\ s = 8m \:$
displacement=8m
Again
$a = \frac{v - u}{t} \\ 4 = \frac{v - 20}{2} \\ v = 20 + 8 = 28m {s}^{ - 1}$