You throw a water balloon downward from the roof of a building at a speed of 3.5 m/s. How fast will the balloon be moving when it hits the sidewalk 8.0 m below?

a. 13 m/s

c. 160 m/s

b. 12.7 m/s

d. 169 m/s

From the given problem above, the correct answer would be option A. 13 m/s. Here's how it is solved. Equation Vf (Final Velocity) = Square root of Vo^2 (initial velocity) + 2 (9.81) (8m) = 12.97m/s round it up to 13m/s. Therefore, if the balloons will be moving and it hits the sidewalk 8.0m below, then it is 13 m/s fast.