MCQ
A ball thrown vertically upwards falls back on the ground after  $6$ second. Assuming that the equation of motion is of the form $s = ut - 4.9{t^2}$, where s is in metre and  $t$ is in second, find the velocity at $t = 0$ .......... $m/s$.
  • A
    $0$
  • B
    $1$
  • $29.4$
  • D
    None of these

Answer

Correct option: C.
$29.4$
c
(c) Velocity of ball $(v) =\frac{{ds}}{{dt}} = $$u - 9.8\,t$

Here terminal velocity $v = 0$ and $t = 3\,sec$

$u = 9.8(3) = 29.4 \,m/sec$.

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