6 (a) In the absence of air resistance, a golf ball projected from the point P follows a parabolic path and lands at the point Q. The initial velocity of the ball is u and at an angle of a with the horizontal. P (i) Derive an expression for the horizontal distance PQ in terms of u, a, and the acceleration due to gravity g (ii) What is the value of the angle of projection a for the distance PQ to be maximum? (b) A motorcycle stuntman who is moving horizontally takes off from a point 15.0 m above the ground and lands 60.0 m away as shown in the figure. 15.0 m -60.0 m Calculate (i) the time between taking off and landing (ii) the speed of the motorcycle at take-off.