JEE MainPhysicsMotion in Two Dimensions
Two projectiles are fired from the ground with the same initial speed, and they cover the same horizontal range. The ratio of their minimum speeds during flight is 1 : 3 . If the sum of their times of flight is 8 s, the maximum height reached by the projectile that has the longer time of flight is (Take g = 10 m/s ^2 )
Options
- A5 m
- B45 m
- C50 m
- D180 m
Correct answer
B. 45 m
Step-by-step solution
For two projectiles to have the same horizontal range with the same initial speed u , their angles of projection must be and 90^ - . The minimum speed of a projectile occurs at the highest point of its trajectory and is equal to the horizontal component of its velocity, v_ min = u . The ratio of their minimum speeds is given as 1 : 3 . Assuming is the steeper angle (so is smaller): u u (90^ - ) = = = 1 3 This implies = 3 . The times of flight are t₁ = 2u g and t₂ = 2u g . The ratio of their times of flight is: t₁ t