The initial speed of the second ball if they are both reach the ground at the same time is 19.8 m/s.
The initial speed of the second ball is calculated as follows;
v = √2gh
v = √(2 x 9.8 x 45)
v = 29.7 m/s
t = √(2h/g)
t = √(2 x 5/9.8)
t = 1.01 s
vf = vi + gt
29.7 = vi + 9.8(1.01)
29.7 = vi + 9.9
vi = 19.8 m/s
Thus, the initial speed of the second ball if they are both reach the ground at the same time is 19.8 m/s.
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