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**1. Homework Statement**

A stone is thrown horizontally from a cliff on a different planet with a speed of 10 m/s. The cliff has height 200m, and takes 4 s to hit the ground. Assume no air friction. What is the acceleration due to gravity on this planet.

**2. Homework Equations**

Δy = v

_{0}t + 1/2 at

^{2}

**3. The Attempt at a Solution**

I thought the initial vertical velocity would be 0 since it's thrown horizontally, so the first term of the equation disappears. And they give you t = 4, so I did 200*2/16 = 25 m/s^2.

But apparently the answer is 5 m/s^2.

Why?