A cannon and a target are 5.10 km apart and located at the same level. How soon will the shell launched with the initial velocity 240 m/s reach the target in the absence of air drag ?

A cannon and a target are 5.10 km apart and located at the same level.

1.	A cannon and a target are 5.10 km apart and located at the same level. How soon will the shell launched with the initial velocity 240 m/s reach the target in the absence of air drag ?
Answer» Solution :Here, `v_(0) = 240 ms^(-1), R = 5.10 km = 5100 m`, `g = 9.8 ms^(-2), ALPHA = ? ""R = (v_(0)^(2) sin 2 alpha)/(g)` `sin 2 alpha = (Rg)/(v_(0)^(2)) ""rArr alpha = 30^(@)` or `60^(@)` using `= T = (2v_(0)sin alpha)/(g)` when, `alpha = 30^(@) , T_(1) = (2 xx 240 xx 0.5)/(9.8) = 24.5 s` When, `alpha = 60^(@), T_(2) = (2 xx 240 xx 0.867)/(9.8) = 42.41s`