Question

n the figure shown, the two projectiles are fired simultaneously. What should be the initial speed of the left side projectile for the two projectiles to hit in mid-air?

Answer 1

Answer:

$20\sqrt{\frac{2}{3}}\:m/s$

Explanation:

Figure is attached

1) We know,

when two projectiles are fired simultaneously , they collide in air when vertical component of initial velocity is equal.

2) That is,

In our case,  

$u_{1y}=u_{2y}\\ \\=>u*sin(60^{\circ})=20sin(45^{\circ})\\ \\=>u*\frac{\sqrt{3}}{2}=20*\frac{1}{\sqrt{2}}\\ \\=>u=\frac{20*2}{\sqrt{2}*\sqrt{3}}=20\sqrt{\frac{2}{3}}\:m/s$

Hence,

Initial speed of the left side projectile for the two projectiles to hit in mid-air is $20\sqrt{\frac{2}{3}}\:m/s$