Match the columns

Column $-I$     $R/H_{max}$	Column $-II$   Angle of projection $\theta $
$A.$ $1$	$1.$ ${60^o}$
$B.$ $4$	$2.$ ${30^o}$
$C.$ $4\sqrt 3$	$3.$ ${45^o}$
$D.$ $\frac {4}{\sqrt 3}$	$4.$ $tan^{-1}\,4\,=\,{76^o}$

 

Trajectory of particle in a projectile motion is given as $y=x-\frac{x^2}{80}$. Here, $x$ and $y$ are in metre. For this projectile motion match the following with $g=10\,m / s ^2$.

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Two balls are projected from the same point simultaneously.First ball is projected vertically upwards and the second ball at an angle of projection $60^o$ to the ground level. Both the balls reach the ground simultaneously. The ratio of their velocities are

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For a given velocity, a projectile has the same range $R$ for two angles of projection if $t_1$ and $t_2$ are the times of flight in the two cases then