MCQ
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 ........ $^o$ $(g = 10m/{\sec ^2})$
- ✓${30}$
- B${45}$
- C${50.2}$
- D${60}$
✓
Answer
Correct option: A.
${30}$
a
(a) For vertical upward motion $h = ut - \frac{1}{2}g{t^2}$
(a) 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 $
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