MCQ
For a given velocity, a projectile has the same range $R$ for two angles of projection if $t$ and $t$ are the times of flight in the two cases then[KCET 2003
  • A
    $t_1 t_2 \propto R^2$
  • $t_1 t_2 \propto R$
  • C
    $t_1 t_2 \propto \frac{1}{R}$
  • D
    $t_1 t_2 \propto \frac{1}{R^2}$

Answer

Correct option: B.
$t_1 t_2 \propto R$
(b) For same range angle of projection should be $\theta$ and 90- $\theta$So, time of flights $t_1=\frac{2 u \sin \theta}{g}$ and$t_2=\frac{2 u \sin (90-\theta)}{g}=\frac{2 u \cos \theta}{g}$
$\text { By multiplying }=t_1 t_2=\frac{4 u^2\sin \theta \cos \theta}{g^2} t_1 t_2=\frac{2}{g} \frac{\left(u^2 \sin 2\theta\right)}{g}=\frac{2 R}{g}$
$\Rightarrow t_1 t_2 \propto R$

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