Q.

Two projectiles are fired from ground with same initial speeds from same point at angles (45° + α) and (45° – α) with horizontal direction. The ratio of their times of flights is          [2025]

1 1  
2 1tanα1+tanα  
3 1+sin2α1sin2α  
4 1+tanα1tanα  

Ans.

(4)

Time of flight for 1st projectile,

T1=2u sin(45+α)g

Time of flight for 2nd projectile,

T2=2u sin(45α)g

T1T2=sin(45+α)sin(45α)

T1T2=12cosα+12sinα12cosα12sinα

T1T2=cosα+sinαcosαsinα=1+tanα1tanα