Question

Two stones are projected with same velocity $v$ at an angle $\theta \&(90-\theta) .$ If $H$ and $H_{1}$ are the greatest heights in the two paths, what is the relation between $R, H$ and $H_{1} ?$

• A. $R=4\sqrt{H{{H}_{1}}}$
• B. $R=\sqrt{H{{H}_{1}}}$
• C. $R=4\,H{{H}_{1}}$
• D. None of the above

Answer 1

Answer: (A)

$R=4\sqrt{H{{H}_{1}}}$

Answer 2

Range of projectile $R =\frac{2 u^{2} \sin \theta \cos \theta}{g} \ldots$(1) Height $H=\frac{u^{2} \sin ^{2} \theta}{2 g} \ldots$(2) $H_{1}=\frac{u^{2} \sin ^{2}(90-\theta)}{2 g}=\frac{u^{2} \cos ^{2} \theta}{2 g}\ldots$(3) Then, $H H_{1}=\frac{u^{2} \sin ^{2} \theta u^{2} \cos ^{2} \theta}{2 g 2 g}\ldots$(4) From E (1), we get $R^{2} =\frac{4 u^{2} \sin ^{2} \theta u^{2} \cos ^{2} \theta \times 4}{2 g \times 2 g}$ $R =\sqrt{16 HH _{1}}$ [from E $(4) ]$ $=4 \sqrt{ HH _{1}}$