A ball is thrown vertically upward with a constant speed of 15m/s. determine the line of flight when it returns to its original position.

u = 15 m/s 

a = -10m/s^2

v  = 0 m/s

 

v = u +at

0 = 15-10t

t  = 1.5 sec

As the ball will return to its original position, the time taken for the ball to go up will be same as that it will take to come down. 

 

Hence total time taken = 3 sec.