A stone is projected from the ground with

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A stone is projected from the ground with velocity $25\,m/s$. Two seconds later, it just clears a wall $5 \,m$ high. The angle of projection of the stone is ........ $^o$ $(g = 10m/{\sec ^2})$

A

${30}$

B

${45}$

C

${50.2}$

D

${60}$

A stone is projected from the ground with velocity $25\,m/s$. Two seconds later, it just clears a wall $5 \,m$ high. The angle of projection of the stone is ........ $^o$ $(g = 10m/{\sec ^2})$

For vertical upward motion $h = ut - \frac{1}{2}g{t^2}$

$5 = (25\sin \theta ) \times 2 - \frac{1}{2} \times 10 \times {(2)^2}$

$⇒$ $25 = 50 \sin \theta $ 

$⇒$ $\sin \theta = \frac{1}{2}$

$⇒$ $\theta = 30^\circ $