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Q.
Find the total displacement of a body in $8\, s$ Starting from rest with an acceleration of $20\, cm/s^2$.
AFMCAFMC 2000
Solution:
When a body starts from rest its initial velocity is zero.
Using 2nd equation of motion, we have
$s=u t+\frac{1}{2} a t^{2}$
where, $s$ is displacement undergone,
$u$ is initial velocity,
$a$ is acceleration due to gravity and $t$ is time
Since, body starts from rest, so $u=0$
Here, $a=20 \,cm / s ^{2}, t=8 \,s$
$\therefore s=0+\frac{1}{2} \times 20 \times 8 \times 8=640\, cm$