a ball was 2.0 m off the ground and thrown horizontally. it traveled for 7.8 m before it hit the ground. what was the imitial speed of the ball

12 m/s

Explanation:

First, find the time it takes for the ball to fall 2.0 m.

y = y₀ + v₀ t + ½ at²

0 = 2.0 + (0) t + ½ (-9.8) t²

0 = 2 - 4.9t²

t = 0.639

Find the velocity needed to travel 7.8 m in that time.

x = x₀ + v₀ t + ½ at²

7.8 = 0 + v₀ (0.639) + ½ (0) (0.639) ²

7.8 = 0.639 v₀

v₀ = 12.2

Rounded to two significant figures, the initial velocity is 12 m/s.