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 240m/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 240m/s reach the target in the absence of air drag?
Answer» Solution :Here, `v_(0)=240ms^(-1)`,R5.10km5100m, `g=9.8ms^(-2), alpha=?""R+(v_(0)^(2)sin2alpha)/(g)` `sin2alpha=(Rg)/(V_(0)^(2))""rArralpha=30^(@) or 60^(@)` using = `T =(2v_(0)sinalpha)/(g)` When, `alpha = 30^(@), T_(1)=(2xx240xx0.5)/(9.8)=24.5s` When,`alpha=60^(@), T_(2)=(2xx240xx0.867)/(9.8)=42.42s`