Answer:
Step 1: Calculate the time it takes for the first stone to reach the water surface using the equation h = (1/2)gt^2, where h is the height, g is the acceleration due to gravity (9.8 m/s^2), and t is the time.
45 = (1/2)(9.8)t^2
t^2 = 45 * 2 / 9.8
t^2 = 9.18
t ≈ 3.03 s
Step 2: Since the second stone is thrown 1 second after the first stone is dropped, the time it takes for the second stone to reach the water surface is t - 1.
t - 1 ≈ 3.03 - 1
t - 1 ≈ 2.03 s
Step 3: Use the equation v = u + gt, where v is the final velocity, u is the initial velocity, g is the acceleration due to gravity, and t is the time.
v = 0 (since the final velocity is zero when the stone reaches the water surface)
u = ?
g = 9.8 m/s^2
t = 2.03 s
0 = u + (9.8)(2.03)
u = -9.8(2.03)
u ≈ -19.894 m/s