Question

The ceiling of a hall is $40m$ high. For maximum horizontal distance, the angle at which the ball can be thrown with a speed of $56m{s}^{-1}$ without hitting the ceiling of the hall is:

• A. ${25}^{\circ }$
• B. ${30}^{\circ }$
• C. ${45}^{\circ }$
• D. ${60}^{\circ }$

Answer 1

Answer: (B)

${30}^{\circ }$

Height covered,

$h=\frac{u^2{\sin }^2\theta }{2g}$

${\sin }^2\theta =\frac{2gh}{u^2}$

$=\frac{2\times 9.8\times 40}{56\times 56}$

$=\frac{784}{56\times 56}$

$\sin \theta =\frac{28}{56}$

$\sin \theta =\frac{1}{2}$

$\theta ={30}^0$