Answer:
u = 9.017m/s
Explanation:
We are told what to look for but we can calculate the velocity of the ball. According to the equation of motion;
S = ut + 1/2gt²
u is the velocity
g is the acceleration due to gravity = -9.81m/s² (upward direction of ball)
t is the time = 7s
15 = 7t - 1/2(9.81)²
15 = 7u -48.118
15+48.118 = 7u
63.118 = 7u
u = 63.118/7
u = 9.017m/s
Hence the velocity of the ball is 9.017m/s