Resultant Velocity Quick Question

1. Nov 11, 2007

lilstar

1. The problem statement, all variables and given/known data
I was wondering, when an object's motion is in the shape of a parabola, and it lands at the same height that it was shot from.. why would the initial velocity and the angle from the ground at which it was shot from.. be equal to the final velocity at which it hit the ground?

2. Relevant equations

3. The attempt at a solution

Would it be because of its parabolic shape?

2. Nov 11, 2007

kbaumen

Because both when moving upwards and downwards the same gravitational force is working on the object. It's acceleration is always ~9.8 m/s$$^{2}$$ and directed to earth's center.