You throw a snowball horizontally. It hits a target 2 meters away. You notice that it hit o.9m below where you aimed. With what horizontal velocity did you throw the snowball?

The snowball travels a horizontal distance x and has height y at time t according to

x = vt

y = 0.9 m - 1/2 gt ²

where g = 9.8 m/s² is the magnitude of the acceleration due to gravity.

Set y = 0 and solve for t :

0 = 0.9 m - 1/2 gt ²

t ² = (1.8 m) / g

t ≈ 0.43 s

The target is 2 m away from where the snowball is thrown, so it was thrown with speed v such that

2 m = v (0.429 s)

v = (2 m) / (0.43 s)

v ≈ 4.7 m/s