Question

A body is projected vertically up with speed of 20m/s . the displacement of it is 3sec is

Answer 1

☸GIVEN:
u=initial speed=20m/s
a=g=-9.8m/s^2
{here we use -ve value as g is directed downwards and we take upward direction to be +ve}
t=3seconds=time

☸ASKED: s=displacement=? in 3seconds
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☸ANSWER:
as we know...
$s = ut + \frac{1}{2} a {t}^{2}$
$s = (20 \times 3) + \frac{1}{2} ( - 9.8) {3}^{2}$
$s = 60 - 44.1= 15 .9m$
so... displacement in 3sec = 15.9m

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hope it helps you...
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