Question

The maximum height reached by projectile is 4m . The horizontal range is 12 m. The velocity of projection in m/s is (gis acceleration due to gravity )

Answer 1

H  = (R tan Ф ) / 4 
4  = (12 tan Ф ) / 4

tan Ф = 4/3       
sin 2Ф = 2 tan Ф / (1 + tan² Ф)  = 24/25


R = u² sin 2Ф / g  
u² =  12* g *25/24 = 50
$u = 5 \sqrt{10} m{s}^{2}$