h.c. verma page no: 53  q.no; 43 

You need to appy Projectile concept in this Q....

a)

Time take by truck 2 move 58.8 m = 58.8/14.7 = 4 sec.

there4 total time take by ball to rech highest point = half of this time = 4/2=2 sec.

now, v=u-gt

there4,    0=u-9.8*2

there4,    u = 19.6

b)

now d resultant velocity of ball = [(V_x) + (V_y)]^1/2

                                                       = [(14.7)² + (19.6)²]^1/2

                                                       = 24.5 m/s

and, 

= V_y/V_x = 19.6/14/7 = 53⁰