A boy playing on the roof of a 10 ~m high building throws a ball with a speed of 10 ~m / s at an angle of 30^ ^ with the horizontal. How far from the throwing point will the ball be at the height of 10 ~m from the

JEE Main 2003

JEE Main 2003 · Physics · Motion in Two Dimensions

A boy playing on the roof of a 10 ~m high building throws a ball...

A boy playing on the roof of a

10 \mathrm{~m}

high building throws a ball with a speed of

10 \mathrm{~m} / \mathrm{s}

at an angle of

30^{{}^{\circ}}

with the horizontal. How far from the throwing point will the ball be at the height of

10 \mathrm{~m}

from the ground?

\left[\mathrm{g}=

\mathrm{~m}

\mathrm{s}^

2, \sin 30^{{}^{\circ}}=

\frac{1}{2}, \cos

30^{{}^{\circ}}=

\frac{\sqrt{3}}{2}\right]

D. $8.66 \mathrm{~m}$

From, the question if the horizontal distance is none other than the horizontal range on the level of the roof of building

\text{ Range }=\frac{\mathrm{u}^2 \sin 2 \theta}{\mathrm{g}}=\frac{(10)^2 \sin (2 \times 30)}{\mathrm{g}}=\frac{10 \times 10 \times \sqrt{3}}{2 \times 10}=

8.66