The equations of motion of a projectile are given by $x=36 t$ metre and $2 y=96 t-9.8 t^2$ metre. The angle…

The equations of motion of a projectile are given by $x=36 t$ metre and $2 y=96 t-9.8 t^2$ metre. The angle of projection is :
  1. $\sin ^{-1}\left(\frac{4}{5}\right)$
  2. $\sin ^{-1}\left(\frac{3}{5}\right)$
  3. $\sin ^{-1}\left(\frac{4}{3}\right)$
  4. $\sin ^{-1}\left(\frac{3}{4}\right)$

Solution

$x=36 t$ metre $2 y=\left(96 t-9.8 t^2\right)$ metre Standard equations are, $x=(u \cos \theta) t$ $y=u \sin \theta t-\frac{1}{2} g t^2$ $u \cos =36$ $u \sin \theta=\frac{96}{2}=48$ $\therefore \quad \tan \theta=\frac{u \sin \theta}{u \cos \theta}=\frac{48}{36}=\frac{4}{3}$ $\theta=\tan ^{-1} \frac{4}{3}$ or $\theta=\sin ^{-1} \frac{4}{5}$

Asked in: AP EAMCET 2003

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