A ball is projected from origin with speed 20 m/s at an angle 30 degree with x axis The - Physics - Motion In A Plane

Question

A ball is projected from origin with speed 20 m/s at an angle 30
degree with x axis The x coordinate of the ball at the instant when
the velocity of the ball becomes perpendicular to the velocity of
projection will be?

Ved Prakash Lakhera · Accepted Answer

The velocity of projection u= 20m/s, angle of projection=30°, the angle made byprojectile with x-axis after time t =90°-30°=60°
therefore usin60° = u sin30° -gt
                20 ×32=-20×12+9
8×t    (1)
eqn 1 is the condition when body comes down but usin30° is the velocity of going up, so taken negative
or       9
8× t = 103 +10=17 32+10=27 32t=27 32/9
8 =2 78 s
therefore x coordinate at that time =u cos30°t=20×3/2×2
78=10×1 732×2
78      x = 17 32×2
78 =48 15m

A ball is projected from origin with speed 20 m/s at an angle 30 degree with x axis. The x coordinate of the ball at the instant when the velocity of the ball becomes perpendicular to the velocity of projection will be?