Question

A ball is projected from ground with a speed of 20ms^-1 at an angle of 30° with horizontal. It just grazes past the edge of a vertical wall of height 1.8 m. The ratio of the distance of point of projection of ball from wall and the distance of point where it hits ground from the wall is (g = 10ms^-2)

(1) 1/9

(2) 1/10

(3) 9/10

(4) 8/9

Answer 1

(1) 1/9

Let x be the horizontal distance of wall from point of projection. Let the ball just grazes past top of wall t second after projection. At t = t; y = h = 1.8m. Therefore

Obvisouly,

The distance of the point where ball hits ground from point of projection equals the horizontal range. Therefore,