Answer:
-4.5 m/s
Explanation:
Even without doing calculations, we know that a projectile has the same speed coming down as it did going up at the same height. Since it went up at 4.5 m/s, it returns down at -4.5 m/s.
To prove it with math, use the given information:
v₀ = 4.5 m/s
a = -9.8 m/s²
Δy = 0 m
Find: v
v² = v₀² + 2aΔy
v² = (4.5 m/s)² + 2 (-9.8 m/s²) (0 m)
v = -4.5 m/s
