Prithvi missile is fired to destroy an enemy military base situated on same horizontal level, situated 99 km away. The missile rises vertically for 1 km & then for remainder of flight, it followes parbolic path like a free body under earth's gravity, at an angle of `45^(@)`. Calculate its velocity at beginning of parabolic path. `(g=10 ms^(-2))`

Explanation

for horizontal motion time t
`t= (99xx10^(3))/(u cos 45^(@))`
for vertical
`1xx10^(3)=u sin 45^(@) t=1/2xx10xxt^(2)`
`1xx10^(3)+(u sin 45^(@))/(u sin 45^(@))xx99xx10^(3)=10/2xx((99xx10^(3))^(2)xx2)/u^(2)`
`u^(2)=((99xx10^(3))^(2)xx10)/(100xx10^(3))`
`u=99xx10^(3) sqrt(1/10^(4))=990 ms^(-1)`