There is a tall cylindrical building standing in a field. Radius of the cylinder is `R = 8 m`. A boy standing at A (at a distance of 10 m from the centre of the cylindrical base of the building) knows that his friend is standing at B behind the building. The line joining A and B passes through the centre of the base of the building. Distance between A and B is 50 m. A wants to throw a ball to B but he realizes that the building is too tall and he cannot throw the ball over it. He throws the ball at a speed of `20 m//s` such that his friend at B has to move minimum distance to catch it.

(a) What is the minimum distance that boy at B will have to move to catch the ball?
(b) At what angle to the horizontal does the boy at A throws the ball? Assume that the ball is released and caught at same height above the ground.
[Take `g = 10 m//s^(2)` and `sin^(-1) (0.75) ~= 48.6^(@)`

Answer

(a) `40 m` (b) `24.3^(@)` ot `65.7^(@)`