Question

A stone is projected with velocity 50m/sec at angle 60° to the horizontal. What will be the speed of stone at the time when it makes angle 30° with horizontal?

Answer 1

Answer:

$\boxed{\mathfrak{v = \dfrac{50}{ \sqrt{3} } \: m {s}^{ - 1} }}$

Explanation:

Since there is no horizontal acceleration. So, Horizontal component of velocity will remain same.

(From the figure attached)

$\rm \implies u \: cos {60}^{ \circ} = v \: cos {30}^{ \circ} \\ \\ \rm \implies 50 \times \dfrac{1}{ \cancel{2}} = v \times \dfrac{ \sqrt{3} }{ \cancel{2}} \\ \\ \rm \implies v = \dfrac{50}{ \sqrt{3} } \: m {s}^{ - 1}$

Answer 2

u cos60° = v cos30°

v = u cos60°/cos30°

v = 50/√3

v = 28.86 m/s